U.S. patent application number 10/034865 was filed with the patent office on 2002-06-27 for recording and reproducing device, disk cartridge, and optical disk device.
Invention is credited to Hirokane, Junji, Iwata, Noboru.
Application Number | 20020080689 10/034865 |
Document ID | / |
Family ID | 27554884 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020080689 |
Kind Code |
A1 |
Hirokane, Junji ; et
al. |
June 27, 2002 |
Recording and reproducing device, disk cartridge, and optical disk
device
Abstract
A recording and reproducing device of the present invention is
provided to achieve the object of realizing stable and desirable
recording and reproducing of information by suppressing fluttering
of an optical disk by way of suppressing pressure fluctuation which
is caused, for example, when an objective lens or an optical pickup
with the objective lens is moved. The object is attained by a
transparent stabilizer, provided between a disk and an optical
pickup, which is moved with the optical pickup, and a slider which
is provided to face the transparent stabilizer with the disk in
between. The slider is supported to oscillate, and the surface of
the slider facing the disk is flat. During rotation of the disk,
the slider moves to balance the air pressure between the
transparent stabilizer and the disk with that between the slider
and the disk.
Inventors: |
Hirokane, Junji; (Nara-shi,
JP) ; Iwata, Noboru; (Tenri-shi, JP) |
Correspondence
Address: |
Dike, Bronstein, Roberts & Cushman
130 Water Street
Boston
MA
02109
US
|
Family ID: |
27554884 |
Appl. No.: |
10/034865 |
Filed: |
December 27, 2001 |
Current U.S.
Class: |
369/13.13 ;
720/725; G9B/11.024; G9B/11.033; G9B/11.044; G9B/11.046; G9B/5.23;
G9B/7.086; G9B/7.107; G9B/7.121; G9B/7.131 |
Current CPC
Class: |
G11B 2007/13727
20130101; G11B 7/0937 20130101; G11B 11/10576 20130101; G11B
11/10532 20130101; G11B 7/13927 20130101; G11B 11/10552 20130101;
G11B 11/1058 20130101; G11B 7/122 20130101; G11B 7/1374 20130101;
G11B 5/6005 20130101; G11B 7/24 20130101 |
Class at
Publication: |
369/13.13 ;
369/291 |
International
Class: |
G11B 011/00; G11B
003/70; G11B 005/84; G11B 007/26 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2000 |
JP |
2000-399589 |
Dec 27, 2000 |
JP |
2000-399587 |
Mar 13, 2001 |
JP |
2001-070486 |
Mar 23, 2001 |
JP |
2001-085305 |
Oct 18, 2001 |
JP |
2001-321147 |
Oct 18, 2001 |
JP |
2001321162 |
Claims
What is claimed is:
1. A recording and reproducing device which includes a light
source, focusing means for converging and projecting a laser beam
which was emitted from the light source on a disk, and rotation
driving means for rotating the disk, said recording and reproducing
device comprising: a stabilizing board, provided between the disk
and the focusing means, which is moved with the focusing means.
2. The recording and reproducing device as set forth in claim 1,
wherein said stabilizing board is transparent.
3. The recording and reproducing device as set forth in claim 1,
wherein said stabilizing board has an opening in an optical path of
the laser beam so as to allow passage of the laser beam.
4. The recording and reproducing device as set forth in claim 1,
wherein said disk is flexible.
5. A recording and reproducing device which records and reproduces
information by projecting a laser beam on a disk being rotated,
said recording and reproducing device comprising: a stabilizing
slider which is disposed to face the disk and is supported to
oscillate, a surface of said stabilizing slider facing the disk
being flat.
6. The recording and reproducing device as set forth in claim 5,
further comprising: a stabilizing board which is disposed to face
said stabilizing slider via the disk.
7. The recording and reproducing device as set forth in claim 6,
wherein said stabilizing board is a slider which is supported to
oscillate and has a flat surface facing said stabilizing
slider.
8. The recording and reproducing device as set forth in claim 7,
wherein said slider is a focusing slider which includes focusing
means for focusing a laser beam on the disk.
9. The recording and reproducing device as set forth in claim 8,
wherein said focusing slider includes a first lens and a second
lens which are provided as the focusing means, the first lens and
the second lens being separated from each other by a predetermined
distance, and said focusing slider further includes a piezoelectric
element layer for controlling the distance between the first lens
and the second lens.
10. The recording and reproducing device as set forth in claim 5,
wherein said stabilizing slider includes a magnetic field
generating element for generating a magnetic field.
11. The recording and reproducing device as set forth in claim 6,
wherein said stabilizing board includes an air-core coil for
generating a magnetic field.
12. The recording and reproducing device as set forth in claim 11,
wherein said stabilizing slider includes a soft magnetic
material.
13. The recording and reproducing device as set forth in claim 5,
wherein said disk is flexible.
14. A recording and reproducing device which includes a light
source, focusing means for converging and projecting a laser beam
which was emitted from the light source on a disk, and rotation
driving means for rotating the disk, said recording and reproducing
device comprising: a first stabilizing board, provided between the
disk and the focusing means, which is moved with the focusing
means; and a slider which is disposed to face said first
stabilizing board via the disk and is supported to oscillate, a
surface of said slider facing the disk being flat.
15. The recording and reproducing device as set forth in claim 14,
wherein said first stabilizing board is fixed to the focusing means
via an elastic member having elasticity.
16. The recording and reproducing device as set forth in claim 14,
wherein the focusing means is a complex lens which is composed of
at least two lenses.
17. The recording and reproducing device as set forth in claim 14,
wherein said slider includes a magnetic field generating element
for generating a magnetic field.
18. The recording and reproducing device as set forth in claim 14,
wherein said first stabilizing board is transparent.
19. The recording and reproducing device as set forth in claim 14,
further comprising: a second stabilizing board which is disposed to
face the disk, and to create a space of reduced pressure between
the disk and said second stabilizing board when the disk is
rotating.
20. The recording and reproducing device as set forth in claim 19,
wherein said second stabilizing board has an opening which is used
to position said slider or said first stabilizing board in a
vicinity of the disk when recording or reproducing information.
21. The recording and reproducing device as set forth in claim 14,
wherein the disk is flexible.
22. A recording and reproducing device which includes an optical
pickup for recording and reproducing information by projecting a
laser beam on a disk being rotated, said recording and reproducing
device comprising: a stabilizing board, provided with the optical
pickup, which is disposed to face the disk when the disk is
rotating.
23. The recording and reproducing device as set forth in claim 22,
further comprising a stabilizing slider which is disposed to face
said stabilizing board via the disk and is supported to oscillate,
said stabilizing slider having a flat surface facing said
stabilizing board.
24. The recording and reproducing device as set forth in claim 23,
wherein said stabilizing board is a slider which is supported to
oscillate and has a flat surface facing said stabilizing
slider.
25. The recording and reproducing device as set forth in claim 23,
wherein said stabilizing slider includes a magnetic field
generating element for generating a magnetic field.
26. The recording and reproducing device as set forth in claim 22,
wherein said stabilizing board includes an air-core coil for
generating a magnetic field.
27. The recording and reproducing device as set forth in claim 26,
wherein said stabilizing slider includes a soft magnetic
material.
28. The recording and reproducing device as set forth in claim 22,
wherein the disk is flexible.
29. A recording and reproducing device which includes a light
source, focusing means for converging and projecting a laser beam
which was emitted from the light source on a disk, and rotation
driving means for rotating the disk, said recording and reproducing
device comprising: a first stabilizing board, provided between the
disk and the focusing means, which is moved with the focusing
means; and a slider which is disposed to face said first
stabilizing board via the disk and is supported to oscillate, a
surface of said slider facing the disk being flat, wherein said
first stabilizing board has an opening in an optical path of the
laser beam so as to allow passage of the laser beam.
30. The recording and reproducing device as set forth in claim 29,
wherein said opening is in a form of a bowl on the optical path of
the laser beam passing through said first stabilizing board.
31. The recording and reproducing device as set forth in claim 29,
wherein the disk is flexible.
32. A disk cartridge containing a disk used in a recording and
reproducing device which records and reproduces information by
projecting a laser beam on the disk being rotated and which
includes a stabilizing slider which is disposed to face the disk
and supported to oscillate, a surface of the stabilizing slider
facing the disk being flat, the disk being exposed from the disk
cartridge when recording or reproducing information, said disk
cartridge comprising inner wall surfaces which define a stabilizing
board for creating a space of reduced pressure between the disk and
the inner wall surfaces during rotation of the disk.
33. The disk cartridge as set forth in claim 32, wherein a distance
between the disk and each of the inner wall surfaces of the disk
cartridge is not less than 10 .mu.m and not more than 200
.mu.m.
34. A disk cartridge containing a disk in a cartridge used in a
recording and reproducing device which includes a light source,
focusing means for converging and projecting a laser beam which was
emitted from the light source on a disk, and rotation driving means
for rotating the disk, the recording and reproducing device further
including a first stabilizing board, disposed between the disk and
the focusing means, which is moved with the focusing means, a
slider which is disposed to face the first stabilizing board via
the disk and supported to oscillate, a surface of the slider facing
the first stabilizing board being flat, and a second stabilizing
board which is disposed to face the disk and to create a space of
reduced pressure between the disk and the second stabilizing board
when the disk is rotating, the disk being exposed from the
cartridge when recording or reproducing information, wherein the
second stabilizing board of the disk is defined by one of inner
wall surfaces of the cartridge.
35. A disk cartridge containing a disk in a cartridge, the disk
being exposed from the cartridge when recording or reproducing
information, said disk cartridge comprising a second stabilizing
board which is defined by inner wall surfaces of the cartridge and
disposed to face the disk and to create a space of reduced pressure
between the disk and the second stabilizing board when the disk is
rotating.
36. The disk cartridge as set forth in claim 35, wherein a distance
between the disk and each of the inner wall surfaces of the
cartridge is not less than 10 .mu.m and not more than 200
.mu.m.
37. The disk cartridge as set forth in claim 35, wherein the inner
wall surfaces of the cartridge have an opening through which the
disk is exposed when recording or reproducing information, and
which is used to position a first stabilizing board and a slider in
a vicinity of the disk, the first stabilizing board being disposed
between focusing means and the disk used in a recording and
reproducing device, the first stabilizing board being moved with
the focusing means, and the slider being disposed to face the first
stabilizing board via the disk and supported to oscillate, a
surface of the slider facing the first stabilizing board being
flat.
38. A disk cartridge containing a disk in a cartridge used in a
recording and reproducing device which includes an optical pickup
for recording and reproducing information by projecting a laser
beam on a disk being rotated, the recording and reproducing device
further including a stabilizing board, provided with the optical
pickup, which is disposed to face the disk when the disk is
rotating, the disk being exposed from the cartridge when recording
or reproducing information, wherein inner wall surfaces of the
cartridge define a stabilizing board for creating a space of
reduced pressure between the disk and the inner wall surfaces when
the disk is rotating.
39. The disk cartridge as set forth in claim 38, wherein a distance
between the disk and each of the inner wall surfaces of the
cartridge is not less than 10 .mu.m and not more than 200
.mu.m.
40. An optical disk device which records and reproduces information
with respect to an optical disk, comprising: rotation driving means
for rotating an optical disk; a focusing unit for focusing light
from a light source on the optical disk; a support member for
supporting the focusing unit; and a rotation stabilizing board,
fixed to said support member so as to be disposed between said
focusing unit with said support member and the optical disk, for
stabilizing rotation of the optical disk.
41. The optical disk device as set forth in claim 40, wherein the
optical disk is contained in an optical disk cartridge, and the
optical disk cartridge has an inner wall which defines a rotation
stabilizing surface, opposite said rotation stabilizing board with
respect to the optical disk, for further stabilizing rotation of
the optical disk.
42. The optical disk device as set forth in claim 40, wherein said
rotation stabilizing board is fixed to the support member of the
focusing unit via an elastic body.
43. The optical disk device as set forth in claim 40, wherein said
rotation stabilizing board is made of a material which essentially
allows passage of light focused by said focusing unit.
44. The optical disk device as set forth in claim 40, wherein said
rotation stabilizing board is made of a material which does not
allow passage of light focused by said focusing unit, and has a
light passage opening which allows passage of the light.
45. The optical disk cartridge as set forth in claim 41, wherein
said optical disk cartridge includes a first opening through which
said rotation driving means enters the optical disk cartridge, and
a second opening through which at least said focusing unit enters
the optical disk cartridge.
46. The optical disk device as set forth in claim 45, wherein said
optical disk cartridge has a first entire stabilizing surface for
the optical disk over an entire surface of one of inner wall
surfaces opposite a surface provided with the second opening.
47. The optical disk device as set forth in claim 45, wherein said
optical disk cartridge has a first entire stabilizing surface for
the optical disk over an entire surface of one of inner wall
surfaces opposite a surface provided with the second opening, and a
second entire stabilizing surface for the optical disk over an
entire surface of another inner wall surface provided with the
second opening.
48. The optical disk device as set forth in claim 47, wherein a
distance between the optical disk and the first entire stabilizing
surface is not less than 10 .mu.m and not more than 200 .mu.m.
49. The optical disk device as set forth in claim 47, wherein a
distance between the optical disk and the second entire stabilizing
surface is not less than 10 .mu.m and not more than 200 .mu.m.
50. The optical disk device as set forth in claim 40, wherein the
disk is flexible.
51. An optical disk device which records and reproduces information
with respect to an optical disk, comprising: rotation driving means
for rotating an optical disk; a focusing unit for focusing light
from a light source on the optical disk; a support member for
supporting the focusing unit; and a transparent rotation
stabilizing board, fixed to the support member so as to be disposed
between the focusing unit with the support member and the optical
disk, for stabilizing rotation of the optical disk, wherein said
focusing unit includes a first objective lens and a second
objective lens, the first objective lens being fixed to the support
member via the transparent rotation stabilizing board, and the
second objective lens being fixed to the support member via an
actuator for driving the lenses.
52. The optical disk device as set forth in claim 51, further
comprising a rotation stabilizing board, disposed opposite said
transparent rotation stabilizing board with respect to the optical
disk, for further stabilizing rotation of the optical disk.
53. The optical disk device as set forth in claim 52, wherein said
rotation stabilizing board is a slider.
54. The optical disk device as set forth in claim 51, wherein said
transparent rotation stabilizing board is fixed to the support
member of the focusing unit via an elastic body.
55. The optical disk device as set forth in claim 51, wherein: the
actuator for driving the lenses includes a focusing actuator for
driving the lenses for focusing, and a tracking actuator for
tracking, and the support member includes an intermediate support
member for supporting the first objective lens via the transparent
rotation stabilizing board and for supporting the second objective
lens via the focusing actuator, and a main support member for
supporting the intermediate support member via the tracking
actuator.
56. The optical disk device as set forth in claim 53, wherein said
slider includes a magnetic field generating element therein.
57. The optical disk device as set forth in claim 51, further
comprising an entire rotation stabilizing board, disposed opposite
the transparent rotation stabilizing board with respect to the
optical disk, for further stabilizing rotation of the optical
disk.
58. The optical disk device as set forth in claim 51, wherein the
optical disk is contained in an optical disk cartridge, and the
optical disk cartridge has an inner wall which defines an entire
rotation stabilizing surface, opposite said transparent rotation
stabilizing board with respect to the optical disk, for further
stabilizing rotation of the optical disk.
59. The optical disk device as set forth in claim 58, wherein said
optical disk cartridge has an inner wall which defines another
entire rotation stabilizing board, on the side of the transparent
rotation stabilizing board with respect to the optical disk, for
further stabilizing rotation of the optical disk.
60. The optical disk device as set forth in claim 59, wherein a
distance between the optical disk and each of the inner wall
surfaces is not less than 10 .mu.m and not more than 200 .mu.m.
61. The optical disk device as set forth in claim 51, wherein the
optical disk is flexible.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a recording and reproducing
device, disk cartridge, and optical disk device, which can be used
to record and reproduce information in high density, and in
particular to a recording and reproducing device, disk cartridge,
and optical disk for recording and/or reproducing a data signal
with respect to a flexible optical disk.
BACKGROUND OF THE INVENTION
[0002] Optical disks, such as a magneto-optical disk, have been
widely used conventionally to record and reproduce information
using a laser. In recent years, recording density of optical disks
has been increasing to accommodate recording of more information.
Along with this, optical disks have adopted smaller recording
pits.
[0003] In order to read out information from such a high-density
optical disk, the optical pickup needs to focus a light beam in
such a way that the beam spot falls on a small domain of the
optical disk where information is recorded. This makes it possible
to read out information recorded in such a small domain. The
smaller spot size enables recording of more information.
[0004] The spot size is proportional to wavelength .lambda. of the
light source used, and is inversely proportional to numerical
aperture NA of the objective lens. Thus, the spot size of a light
beam can be reduced by either reducing the wavelength .lambda. of
light from the light source, or by increasing the numerical
aperture NA of the objective lens.
[0005] However, reducing the spot size by either of these methods
causes large comatic aberration on the light beam when the optical
disk tilts. The result of this is that the light beam cannot be
accurately focused on the optical disk.
[0006] One conventional approach to solve this problem is to reduce
thickness of the optical disk, and in turn length of optical path
in the optical disk, so as to provide a larger margin of error for
a tilt of the optical disk substrate.
[0007] For example, a CD-ROM has a numerical aperture NA=0.45,
wavelength .lambda.=780 nm, and thickness of the optical disk
substrate 1.2 mm. In contrast, a DVD-ROM has a numerical aperture
NA=0.6, wavelength .lambda.=655 nm, and thickness of the optical
disk substrate 0.6 mm. The DVD-ROM thus employs a light source
which emits light of a shorter wavelength .lambda., an objective
lens with larger numerical aperture NA, and a thinner optical disk
substrate, so as to increase recording capacity and a margin of
error for a tilt of the optical disk substrate.
[0008] However, rigidity of the optical disk substrate weakens when
the thickness of the optical disk substrate is further reduced to
provide more margin of error for a tilt of the optical disk
substrate. In fact, this only worsens the tilt of the optical disk
substrate because weaker rigidity of the optical disk substrate
causes the optical disk substrate to flutter. Therefore, there is a
limit in reducing wavelength .lambda. of light of the light source
and increasing numerical aperture NA of the objective lens.
[0009] In light of this problem, Japanese Unexamined Patent
Publication No. 308059/1998 (Tokukaihei 10-308059) (published date:
Nov. 17, 1998) teaches a recording and reproducing device which
stabilizes rotation of an optical disk to allow for use of a
thinner optical disk, an objective lens with larger numerical
aperture NA, and light of a shorter wavelength .lambda.. FIG. 52
shows a structure of this recording and reproducing device.
[0010] As shown in FIG. 52, the recording and reproducing device is
adapted to record and reproduce information with respect to an
optical disk 401, by including a spindle 405 for rotating the
optical disk 401, an optical pickup 403 for projecting and focusing
a light beam on the optical disk 401, and an stabilizer 402 for
stabilizing rotation of the optical disk 401. The optical disk 401
is very thin and flexible.
[0011] The optical disk 401 has a magnetic center hub 404 which
fixes the optical disk 401 on the spindle 405 by magnetic coupling.
The optical pickup 403 has focusing means such as a complex
objective lens. The stabilizer 402 and the optical pickup 403 are
disposed face to face on the both sides of the optical disk
401.
[0012] To record or reproduce information with respect to the
optical disk 401, the optical disk 401 is rotated in the vicinity
of the stabilizer 402. Here, a space of reduced pressure is created
between the optical disk 401 and the stabilizer 402. Thus, the
optical disk 401, being flexible, is drawn toward the stabilizer
402, and rotates at a constant distance from the stabilizer 402. As
a result, fluttering of the optical disk 401 is suppressed, thereby
recording and reproducing information in the recording and
reproducing device with the optical pickup 103 having a wavelength
of light not more than 650 nm and numerical aperture NA of the
complex objective lens not less than 0.7.
[0013] Further, the foregoing publication also teaches a recording
and reproducing device which uses a disk cartridge 406 integrally
provided with the stabilizer 402, as shown in FIG. 53. In this
case, the optical pickup 403 is inserted into the disk cartridge
406 through an opening (not shown) of the disk cartridge 406. The
provision of the stabilizer 402 with the disk cartridge 406
suppresses fluttering of the optical disk 401 as in the recording
and reproducing device of FIG. 52, thus realizing recording and
reproducing of information with the thin optical disk 401, the
objective lens with large numerical aperture NA, and light of short
wavelength .lambda..
[0014] Further, the foregoing publication discloses a structure in
which a light beam is focused using a dual objective lens. For
example, in a reproducing device shown in FIG. 54, a flexible
optical disk 501, fixed on a center hub 503, is rotated by a
spindle 504, so that the optical disk 501 is drawn toward the
stabilizer 502 to stably rotate at a constant distance from the
stabilizer 502.
[0015] A light beam 510 from a light source in a light emitting and
detecting unit 505 is reflected at a mirror 506 and focused through
the dual objective lens composed of a first objective lens 507 and
a second objective lens 508 before it strikes the optical disk 501.
The reflected light from the optical disk 501 is detected by a
photodetector provided in the light emitting and detecting unit
505, so as to record or reproduce information with respect to the
optical disk 501.
[0016] The dual lens is driven by a biaxial actuator 509 to carry
out tracking and focusing. With such a reproducing device, a
wavelength of light not more than 650 nm and numerical aperture NA
of the dual lens not less than 0.7 can be realized.
[0017] However, the foregoing arrangement has the following
problems.
[0018] Generally, recording and reproducing of information with
respect to the optical disk employ a focus control whereby a
constant distance is maintained between the optical disk and
focusing means to maintain the laser beam in focus, so that the
surface of the optical disk carrying the information is always
within the depth of focus of the focusing means such as the
objective lens.
[0019] In this manner, a focus control is carried out to record or
reproduce information with respect to the optical disk 401. The
optical pickup 403 approaches the optical disk 401. In this
instance, in the arrangement of the foregoing publication,
regardless of whether it is the recording and reproducing device of
FIG. 52 or the recording and reproducing device using the disk
cartridge 406 as shown in FIG. 53, the surface of the optical
pickup 403 provided with the focusing means such as the objective
lens is the surface facing the optical disk 401, which surface has
relatively large irregularities. Thus, pressure fluctuates around
the focusing means, or around the optical pickup 403, every time
the focusing means is moved during a focus control, which causes
fluctuation of air pressure between the optical pickup 403 and the
optical disk 401. That is, the movement of the focusing means
causes the optical disk 401 to flutter, which prevents stable focus
control.
[0020] Further, in the reproducing device of FIG. 54, the flexible
optical disk 501 fixed on the spindle 504 is rotated by the spindle
504 so that a space of reduced pressure is created between the
flexible optical disk 501 and the stabilizer 502. The reduced
pressure draws the optical disk 501 toward the stabilizer 502 so
that the optical disk 501 stably rotates at a constant distance
from the stabilizer 502. As a result, fluttering of the optical
disk 501 is suppressed, thereby desirably recording or reproducing
information.
[0021] However, because the dual objective lens which is disposed
opposite the stabilizer 502 approaches the flexible optical disk
501 to reproduce information, the pressure between the dual
objective lens and the optical disk 501 fluctuates. This causes the
optical disk 501 to flutter (shudder) and thus prevent desirable
recording and reproducing of information. Similarly, in the
arrangement in which the disk cartridge is integrally provided with
the stabilizer 502, desirable reproducing of information becomes
difficult because the dual objective lens approaches the flexible
optical disk 501.
[0022] Thus, one conventional problem is fluttering of the optical
disk which is caused by pressure fluctuation around the optical
disk, for example, due to movement of the focusing means of the
optical pickup during a focus control. This means instable focus
control, and therefore it was difficult to record and reproduce
information desirably.
[0023] Another problem is that fluttering of the disk becomes more
serious as the disk is rotated at higher speed, irrespective of
whether the disk is flexible or not. It was therefore difficult to
record and reproduce information stably.
SUMMARY OF THE INVENTION
[0024] An object of the present invention is to provide a recording
and reproducing device, a disk cartridge, and an optical disk
device, which can be used to record and reproduce information both
stably and desirably with less fluttering, even at a high
rotational speed, by suppressing fluttering of an optical disk by
way of suppressing pressure fluctuation which is caused, for
example, when an objective lens is moved.
[0025] In order to achieve this object, a recording and reproducing
device of the present invention, in a recording and reproducing
device which records and reproduces information by projecting a
laser beam on a disk being rotated, comprises: a stabilizing slider
which is disposed to face the disk and is supported to oscillate, a
surface of the stabilizing slider facing the disk being flat.
[0026] According to this arrangement, rotation of the disk induces
an air flow between the disk and the stabilizing slider, and air
bearing is created between the stabilizing slider and the disk
because the surface of the stabilizing slider facing the disk is
flat. Further, since the stabilizing slider is supported to
oscillate, the stabilizing slider can be moved in such a way that a
constant distance is always maintained from the disk during
rotation of the disk.
[0027] Thus, the disk rotates at a constant distance from the
stabilizing slider. That is, fluttering of the disk is prevented
even when the disk is rotating at high speed, thus stably recording
and reproducing information.
[0028] Further, in order to achieve the foregoing object, in a disk
cartridge of the present invention which contains a disk in a
cartridge used in the recording and reproducing device, the disk
being exposed when recording and reproducing information, the
cartridge has inner wall surfaces which define a stabilizing board
for creating a space of reduced pressure between the disk and the
inner wall surfaces.
[0029] According to this arrangement, the stabilizing board defined
by the both inner wall surfaces of the disk cartridge suppresses
fluttering of the disk more effectively, thus realizing more stable
and desirable recording and reproducing.
[0030] Further, in order to achieve the foregoing object, an
optical disk device of the present invention, in an optical disk
device which records and reproduces information with respect to an
optical disk, comprises: rotation driving means for rotating an
optical disk; a focusing unit for focusing light from a light
source on the optical disk; a support member for supporting the
focusing unit; and a rotation stabilizing board, fixed to the
support member so as to be disposed between the focusing unit with
the support member and the optical disk, for stabilizing rotation
of the optical disk.
[0031] According to this arrangement, the rotation stabilizing
board for stabilizing rotation of the flexible optical disk is
provided on the focusing unit and the support member of the
focusing unit. This prevents fluttering of the optical disk which
may be caused when the focusing unit and the support member of the
focusing unit are positioned in the vicinity of the optical disk.
As a result, desirable recording and reproducing can be
realized.
[0032] For a fuller understanding of the nature and advantages of
the invention, reference should be made to the ensuing detailed
description taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 is a cross sectional view showing a structure of
relevant part of a recording and reproducing device according to
one embodiment of the present invention.
[0034] FIG. 2 is an enlarged cross sectional view showing the
structure of relevant part of the recording and reproducing device
of FIG. 1.
[0035] FIG. 3 is an enlarged cross sectional view showing the
structure of relevant part of the recording and reproducing device
of FIG. 1 when a magneto-optical disk is used.
[0036] FIG. 4 is an enlarged cross sectional view showing the
structure of relevant part of the recording and reproducing device
of FIG. 1 when a dual lens is used.
[0037] FIG. 5 is an enlarged cross sectional view showing the
structure of relevant part of the recording and reproducing device
of FIG. 1 when a transparent stabilizer is fixed on an optical
pickup via a spring.
[0038] FIG. 6 is a cross sectional view showing a structure of
relevant part of a recording and reproducing device according to
another embodiment of the present invention.
[0039] FIG. 7 is a plan view of a stabilizer.
[0040] FIG. 8 is a cross sectional view showing the structure of
relevant part of the recording and reproducing device of another
embodiment of the present invention when both inner walls of the
cartridge define the stabilizer.
[0041] FIG. 9 is a plan view of the cartridge.
[0042] FIG. 10 is a cross sectional view showing another structure
of the recording and reproducing device of FIG. 8 when a space
inside a disk cartridge is restricted.
[0043] FIG. 11 is a cross sectional view showing a structure of
relevant part of a recording and reproducing device according to
yet another embodiment of the present invention.
[0044] FIG. 12 is a perspective view of a first stabilizer.
[0045] FIG. 13 is an enlarged cross sectional view showing the
structure of relevant part of the recording and reproducing device
of FIG. 11 when a magneto-optical disk is used.
[0046] FIG. 14 is an enlarged cross sectional view showing the
structure of relevant part of the recording and reproducing device
of FIG. 11 when a dual lens is used.
[0047] FIG. 15 is an enlarged cross sectional view showing the
structure of relevant part of the recording and reproducing device
of FIG. 11 when a first stabilizer is fixed on an optical pickup
via a spring.
[0048] FIG. 16 is a cross sectional view showing a structure of
relevant part of a recording and reproducing device according to
still another embodiment of the present invention.
[0049] FIG. 17 is a plan view of a second stabilizer.
[0050] FIG. 18 is a cross sectional view showing the structure of
relevant part of the recording and reproducing device of another
embodiment of the present invention when both inner walls of the
cartridge define the second stabilizer.
[0051] FIG. 19 is a plan view of the cartridge.
[0052] FIG. 20 is a cross sectional view showing another structure
of the recording and reproducing device of FIG. 18 when a space
inside a disk cartridge is restricted.
[0053] FIG. 21 is a cross sectional view schematically showing yet
another embodiment of the optical disk device of the present
invention.
[0054] FIG. 22 is a plan view of an optical disk cartridge of the
optical disk device of FIG. 21.
[0055] FIG. 23 is an enlarged cross sectional view showing a
structure of relevant part of the optical disk device of FIG.
21.
[0056] FIG. 24 is a cross sectional view schematically showing
another structure of the optical disk device.
[0057] FIG. 25 is a cross sectional view schematically showing
still another structure of the optical disk device.
[0058] FIG. 26 is a cross sectional view schematically showing yet
another structure of the optical disk device.
[0059] FIG. 27 is a cross sectional view schematically showing
still another structure of the optical disk device.
[0060] FIG. 28 is a cross sectional view schematically showing yet
another structure of the optical disk device.
[0061] FIG. 29 is a cross sectional view showing a structure of
relevant part of a recording and reproducing device of still
another embodiment of the present invention.
[0062] FIG. 30 is a cross sectional view showing a structure of
relevant part of the recording and reproducing device of FIG.
29.
[0063] FIG. 31 is a plan view showing a structure of relevant part
of the recording and reproducing device of FIG. 30.
[0064] FIG. 32 is a cross sectional view schematically showing a
structure of the recording and reproducing device of FIG. 29 when
light is projected from the side of a disk substrate of the
disk.
[0065] FIG. 33 is a cross sectional view schematically showing a
structure of relevant part of the recording and reproducing device
of FIG. 29 when light is projected from the side of a protective
film of the disk.
[0066] FIG. 34 is a cross sectional view schematically showing a
structure of relevant part of the recording and reproducing device
of FIG. 29 when light is projected from the side of a protective
film of the disk.
[0067] FIG. 35 is a cross sectional view showing a structure of
relevant part of the recording device of FIG. 29 when focusing
control is carried out differently from FIG. 29.
[0068] FIG. 36 is a cross sectional view showing a structure of
relevant part of a recording and reproducing device according to
still another embodiment of the present invention when both inner
walls of a cartridge define a stabilizer.
[0069] FIG. 37 is a plan view of the cartridge.
[0070] FIG. 38 is, a cross sectional view showing a structure of
relevant part of the recording and reproducing device of FIG. 29
when a magneto-optical disk is used.
[0071] FIG. 39 is a cross sectional view showing a structure of
relevant part of the recording and reproducing device of FIG. 29
when a magneto-optical disk is used.
[0072] FIG. 40 is a cross sectional view showing a structure of
relevant part of the recording and reproducing device of FIG. 29
when a magneto-optical disk is used.
[0073] FIG. 41 is a cross sectional view schematically showing one
embodiment of an optical disk device of the present invention.
[0074] FIG. 42 is an enlarged cross sectional view showing relevant
part of FIG. 41.
[0075] FIG. 43 is a cross sectional view showing a structure of
relevant part of another embodiment of the optical disk device of
the present invention.
[0076] FIG. 44 is a cross sectional view showing a structure of
relevant part of yet another embodiment of the optical disk device
of the present invention.
[0077] FIG. 45 is a cross sectional view showing a structure of
relevant part of still another embodiment of the optical disk
device of the present invention.
[0078] FIG. 46 is a cross sectional view of the optical disk device
and an entire rotation stabilizer of the present invention.
[0079] FIG. 47 is a plan view of the entire rotation stabilizer of
FIG. 46.
[0080] FIG. 48 is a cross sectional view of the optical disk device
and an optical disk cartridge of the present invention.
[0081] FIG. 49 is a plan view of the optical disk cartridge of FIG.
48.
[0082] FIG. 50 is a cross sectional view of the optical disk device
and an optical disk cartridge of the present invention.
[0083] FIG. 51 is a plan view of the optical disk cartridge of FIG.
50.
[0084] FIG. 52 is a cross sectional view showing a structure of
relevant part of a conventional recording and reproducing
device.
[0085] FIG. 53 is a cross sectional view showing a structure of
relevant part of a recording and reproducing device using a
conventional cartridge.
[0086] FIG. 54 is a cross sectional view showing how light is
projected in the recording and reproducing device of FIG. 52.
DESCRIPTION OF THE EMBODIMENTS
[0087] [First Embodiment]
[0088] The following will explain one embodiment of the present
invention. Note that, the following embodiments will describe the
case where the present invention is applied to a flexible disk, but
the present invention is also applicable to inflexible disks as
well.
[0089] FIG. 1 is a cross sectional view showing a relevant part of
a recording and reproducing device. As shown in FIG. 1, the
recording and reproducing device according to the present
embodiment includes a spindle (rotation driving means) 3, an
optical pickup 4, a transparent stabilizing board (first
stabilizing board) 5, a support section 6, a slider 7, and a
suspension 8, which are incorporated to record and reproduce
information with respect to a disk 1.
[0090] The transparent stabilizing board 5 is integrally fixed on
an upper portion of the optical pickup 4. The optical pickup 4 with
the transparent stabilizing board 5 is provided at a predetermined
distance from one surface of the disk 1, and the slider 7 is
disposed above the other surface of the disk 1 on the opposite side
of the transparent stabilizing board 5 and the optical pickup 4.
The optical pickup 4 and the slider 7 are integrally provided via
the support section 6 and the suspension 8 which together make up a
support member.
[0091] The disk 1 is a thin flexible disk made of transparent
resin. Further, the disk 1 has a magnetic center hub 2, whereby the
disk 1 is chucked to the spindle 3 by magnetic coupling. The disk 1
is rotated by driving the spindle 3 by a motor (not shown).
Information is recorded and reproduced as the disk 1 rotates.
[0092] Note that, the type of disk 1 is not particularly limited as
long as it is a flexible optical disk. For example, the disk 1 may
be a ROM (Read-Only Memory) disk with a series of pits, which are
recessions on a surface of the disk substrate; or a write once disk
which incorporates an organic pigment material as the recording
medium; or a rewritable optical disk which incorporates a phase
change material as the recording medium.
[0093] Here, it is assumed that the disk 1 is a write once disk or
a rewritable optical disk. As shown in FIG. 2, the disk 1 includes
a disk substrate 1a with guiding grooves which are recessed and
raised portions on a surface of the disk, a recording medium 1b
which is formed on the surface of the recessed and raised guiding
grooves; and a protecting layer 1c for protecting the recording
medium 1b.
[0094] As shown in FIG. 2, the optical pickup 4 includes an optical
pickup casing 15. In the optical pickup casing 15 are provided an
light emitting and detecting optical system (light source) 10, a
biaxial actuator 14, a lens holder 13, and an objective lens
(focusing means) 12.
[0095] The light emitting and detecting optical system 10 includes
a light emitting element which makes up a light source to emit a
laser beam 11 in a direction toward the disk 1. The biaxial
actuator 14 is provided on the optical pickup casing 15 to support
the lens holder 13. The lens holder 13 is provided to hold the
objective lens 12 between the light emitting and detecting optical
system 10 and the transparent stabilizing board 5 which is provided
on the optical pickup 4.
[0096] The electromagnetic force generated by coils provided in the
biaxial actuator 14 drives the objective lens 12 in such a way that
the objective lens 12 is freely displaced in focusing directions
(vertical direction with respect to the disk 1) and in tracking
directions (directions indicated by arrows in FIG. 1) with respect
to the guiding grooves of the disk 1, thereby enabling the
objective lens 12 to accommodate fluttering of the disk 1 or
eccentricity of the tracks formed on the disk 1, in case where the
recording and reproducing device is disturbed, for example, by
oscillation.
[0097] The laser beam 11 emitted by the light emitting and
detecting optical system 10 is focused through the objective lens
12 to irradiate the disk 1. The leaser beam 11 on the disk 1 is
reflected at the recording medium 1b of the disk 1. The light
reflected at the recording medium 1b travels back to the light
emitting and detecting optical system 10 through the objective lens
12. The light in the light emitting and detecting optical system 10
is detected by a photoreceptor element (not shown) therein, thereby
recording or reproducing information.
[0098] The transparent stabilizing board 5 is provided on the
optical pickup 4, i.e., on the surface of the optical pickup 4 on
the side of the disk 1, at a predetermined distance from the disk
1. The optical pickup 4 and the transparent stabilizing board 5 are
linked to each other. The transparent stabilizing board 5 is made
of a transparent material to allow transmission of the laser beam
11 which is emitted by the optical pickup 4 to irradiate the disk
1.
[0099] The support section 6 is fixed to the optical pickup 4 at
one end, and on the other end to the suspension 8 which leads to
the slider 7 toward the tip. The support section 6 is driven by a
linear motor (not shown) to guide the optical pickup 4 and the
slider 7 to a predetermined position of the disk 1. This brings
about integral movement of the transparent stabilizing board 5 and
the slider 7 which are linked to the optical pickup 4.
[0100] The slider 7, supported by the suspension 8 and provided
opposite the transparent stabilizing board 5 via the disk 1, can
oscillate relative to the support section 6 in a vertical direction
with respect to the surface of the disk 1. The surface of the
slider 7 facing the transparent stabilizing board 5 is flat. When
recording or reproducing information with respect to the disk 1,
i.e., during rotation of the disk 1, the rotation of the disk 1
induces an air flow between the disk 1 and the slider 7, with the
result that the air pressure between the slider 7 and the disk 1 in
increased because the surface of the slider 7 facing the disk 1 is
flat. That is, pressure is created between the slider 7 and the
disk 1. In the same manner, rotation of the disk 1 also induces an
air flow between the disk 1 and the transparent stabilizing board 5
to create pressure therebetween. In addition, the slider 7 is
supported to oscillate. Thus, the slider 7 can be moved to balance
out the air pressure between the disk 1 and the transparent
stabilizing board 5 with that between the slider 7 and the disk
1.
[0101] By this pressure-induced state and balancing of it between
(1) the slider 7 and the disk 1 and (2) the transparent stabilizing
board 5 and the disk 1, the disk 1 rotates at a predetermined
distance from the slider 7 and the transparent stabilizing board 5.
This suppresses fluttering of the disk 1 when it is rotating,
thereby stabilizing rotation of the disk 1.
[0102] Note that, when the surface of the slider 7 facing the
transparent stabilizing board 5 is flat as in the foregoing case,
the rotation of the disk 1 induces an air flow between the disk 1
and the slider 7 to create pressure therebetween. However, the
pressure between the slider 7 and the disk 1 is reduced when the
surface of the slider 7 facing the transparent stabilizing board 5
has a groove which acts to drain the air out of the gap between the
slider 7 and the disk 1 when the disk is rotating.
[0103] Generally, recording and reproducing of information with
respect to the disk 1 employ a focus control which keeps the laser
beam 11 in focus by maintaining a constant distance between the
disk 1 and the objective lens 12, so that the recording medium 1b
of the disk 1 is always within a depth of focus of the objective
lens 12.
[0104] Here, as shown in FIG. 52, when a disk 401 and an optical
pickup 403 are directly face to face with nothing in between, the
surface of the optical pickup 403 facing the disk 401 makes up a
surface with focusing means such as an objective lens, for example.
Such a surface has relatively large irregularities, which cause the
pressure to fluctuate around the focusing means every time the
focusing means is moved during the focus control. Thus, the air
pressure between the focusing means and the disk 401 easily
fluctuates with the result that the disk 401 flutters in response
to the movement of the focusing means.
[0105] However, according to the arrangement as shown in FIG. 1,
since the transparent stabilizing board 5 is placed between the
disk 1 and the objective lens 12, the surface of the optical pickup
4 facing the disk 1 becomes flat by the flat surface of the
transparent stabilizing board 5. As a result, the air pressure
between the flat surface of the transparent stabilizing board 5 and
the disk 1 becomes evenly distributed. This suppresses fluctuation
of air pressure between the transparent stabilizing board 5 and the
disk 1 even when, for example, the objective lens 12 is moved to
carry out the focus control, thus suppressing fluttering of the
disk 1.
[0106] Further, because the slider 7 is supported in such a way
that it can oscillate in a vertical direction with respect to the
disk 1, fluctuation of air pressure between the disk 1 and the
transparent stabilizing board 5, which may be caused, for example,
when the optical pickup 4 with the objective lens 12 is moved
during the focus control, can be compensated for by varying the air
pressure between the disk 1 and the slider 7 in such a manner that
it is balanced with the air pressure between the disk 1 and the
transparent stabilizing board 5.
[0107] Thus, even in cases where the objective lens 12 is moved
relative to the disk 1, or the transparent stabilizing board 5 is
moved with the optical pickup 4, the slider 7 accommodates this
movement to follow the disk 1, so as to balance air pressure
between the disk 1 and the transparent stabilizing board 5 with
that between the disk 1 and the slider 7. Further, since the
surface of the slider 7 facing the disk 1 is flat, the air pressure
between the slider 7 and the disk 1 can be balanced easily and
stably. As a result, it is possible to suppress displacement of the
disk 1 in a vertical direction due to pressure fluctuation around
the disk 1, i.e., fluttering of the disk 1 can be suppressed. This
makes it possible to stably and easily carry out a focus control,
or tracking of the disk 1 with the laser beam 11 in the track
direction, even when the biaxial actuator 14 employing the
conventional servo technique is used.
[0108] As a result, rotation of the disk 1 can be stabilized even
when the objective lens 12 or the optical pickup 4 is moved, thus
providing a recording and reproducing device which is capable of
recording and reproducing information stably and desirably even
when the disk 1 is a thin disk. Further, with a thin disk, the
optical path length in the disk 1 can be made shorter, which
increases a margin or error for a tilt of the disk 1. As a result,
recording density of the disk 1 can be increased.
[0109] Note that, not limiting to the optical disk, the disk 1 may
be, for example, a magneto-optical disk which uses a
magneto-optical recording medium as the recording medium 1b.
[0110] Referring to FIG. 3, the following describes an example of a
recording and reproducing device which uses a magneto-optical disk
as the disk 1 to record and reproduce information. Recording of
information on a magneto-optical disk requires a recording magnetic
field. A recording magnetic field needs to be applied to an area
where the laser beam 11 is focused. To this end, a magnetic head
(magnetic field generating element) 30 is embedded in the slider 7.
The structure of the recording and reproducing device other than
the slider 7 which is integrally provided with the magnetic head 30
is as already described with reference to FIG. 2.
[0111] When recording information in the disk 1, the laser beam 11
projected on the disk 1 raises temperature of the recording medium
1b which is provided on the disk substrate 1a, thereby reducing
coercive force of the recording medium 1b. Here, the magnetic field
generated by the magnetic head 30 is applied to the disk 1.
[0112] The laser beam 11 emitted from the light emitting and
detecting optical system 10 is converged by the objective lens 12
in the optical pickup 4 to irradiate the disk 1. The coercive force
of the disk 1 is reduced in the foregoing manner, and the magnetic
field generated by the magnetic head 30 changes the magnetization
direction of the disk 1. Here, the magnetic head 30 and the optical
pickup 4 are driven integrally. Information is recorded in the disk
1 in this manner.
[0113] In this way, the provision of the magnetic head 30 in the
slider 7 can realize a recording and reproducing device which can
record and reproduce information using a magneto-optical disk with
a recording medium which requires a magnetic field for
recording.
[0114] As in the structure of FIG. 2, the structure shown in FIG. 3
also includes the transparent stabilizing board 5, as well as the
slider 7 which is provided opposite the transparent stabilizing
board 5 via the disk 1. Thus, pressure fluctuation around the disk
1 and the optical pickup 4 can be suppressed even when the
objective lens 12 or the optical pickup 4 provided with the
objective lens 12 is moved. This stabilizes rotation of the disk 1
and thus provides a recording and reproducing device which can
stably and desirably record and reproduce information even when the
disk 1 is a thin disk.
[0115] Further, the objective lens 12 is not just limited to a
simple lens as shown in FIG. 2, and it may be a dual lens which
incorporates at least two lenses. For example, FIG. 4 shows an
exemplary structure of the recording and reproducing device of FIG.
1, in which a dual lens composed of two lenses is used as the
objective lens 12.
[0116] The dual lens as the objective lens 12 includes a lens 40
and a lens 41. This increases numerical aperture NA of the
objective lens 12. Specifically, with the use of the dual lens, the
numerical aperture NA of the objective lens 12 can be increased to
0.7 or greater, preferably 0.8 to 0.95. This makes it possible to
reduce the spot size of the laser beam 11 projected on the disk 1,
which in turn increases the recording capacity of the disk 1, and
thus density of the disk 1. As a result, the recording and
reproducing device which is suitable for high density recording and
reproducing can be provided.
[0117] The numerical aperture NA of the objective lens 12 can also
be increased using a simple lens. However, the use of the dual lens
allows the objective lens 12 to be manufactured with large
numerical aperture NA. Thus, the dual lens is preferable for the
objective lens 12 when the numerical aperture NA is to be increased
to 0.7 or greater as in the present embodiment.
[0118] Note that, the structure of FIG. 4 includes the magnetic
head 30 and uses a magneto-optical disk as the disk 1. However, an
optical disk may be used as well. In this case, the magnetic head
30 is not required.
[0119] Further, as shown in FIG. 5, the transparent stabilizing
board 5 may be fixed to the optical pickup 4 via a board spring 50
(elastic member). FIG. 5 shows the structure of the recording and
reproducing device of FIG. 3, with the additional member board
spring 50 between the transparent stabilizing board 5 and the
optical pickup 4.
[0120] As shown in FIG. 5, the transparent stabilizing board 5 is
fixed on the optical pickup casing 15 via the board spring 50.
According to the structure of FIG. 5, even when the slider 7
oscillates in response to external force and the disk 1 oscillates
by the pressure created between the disk 1 and the slider 7 in
response to this oscillation of the slider 7, the transparent
stabilizing board 5 can follow the oscillation of the disk 1 by the
stretch and compression of the board spring 50 to balance out the
air pressure between the disk 1 and the transparent stabilizing
board 5 with that between the disk 1 and the slider 7.
[0121] Thus, it is possible to prevent damage to the disk 1 which
may be caused by a collision between the disk 1 and the transparent
stabilizing board 5 due to external oscillation.
[0122] Note that, the board spring 50 is not just limited to a
spring as long as it is elastic. For example, materials such as
rubber or foamed resin may be used instead. Here, as the term is
used, "spring" may be any elastic body. The spring is preferable
because it has a large stroke in response to a load.
[0123] [Second Embodiment]
[0124] The following will describe another embodiment of the
present invention. Note that, constituting elements having the same
functions as those described in the First Embodiment are given the
same reference numerals and explanations thereof are omitted
here.
[0125] FIG. 6 is a cross sectional view showing a relevant portion
of a recording and reproducing device according to the present
embodiment, in which a stabilizing board (second stabilizing board)
60 is added to the structure of FIG. 1. FIG. 7 is a plan view of
the stabilizing board 60. Note that, the cross section of FIG. 6
showing a relevant portion of the recording and reproducing device
is taken along the central line in the radial direction of the
stabilizing board 60 at a second opening 62.
[0126] The stabilizing board 60 is larger than the transparent
stabilizing board 5, and, for example, in the form of a circle
slightly larger than the disk 1, as shown in FIG. 7. Further, the
stabilizing board 60 has a first opening 61 for chucking a center
hub 2 of the disk 1 to a spindle 3, and the second opening 62 which
is used to position an optical pickup 4 with a transparent
stabilizing board 5 in the vicinity of the disk 1. Further, the
stabilizing board 60 in the recording and reproducing device is
fixed at such a position that it is opposite the disk 1 and can
create a space of reduced pressure between the disk 1 and the
stabilizing board 60 when the disk 1 rotates.
[0127] By thus providing the stabilizing board 60 larger than and
separately from the slider 7 or the transparent stabilizing board 5
at a position opposite and in the vicinity of the disk 1, air flows
out from the outer periphery of the stabilizing board 60 when the
disk 1 is rotating, which reduces air pressure between the
stabilizing board 60 and the disk 1. Here, the disk 1, by being
flexible, is drawn to the stabilizing board 60 and rotates at a
constant distance from the stabilizing board 60.
[0128] Thus, the addition of the stabilizing board 60 can further
stabilize rotation of the disk 1, compared with the case where
rotation of the disk 1 is stabilized by providing only the
transparent stabilizing board 5 and the slider 7, which are smaller
than the stabilizing board 60 and are provided within the domain of
the second opening 62 to balance the pressure which is created by
the air flowing into the space between the transparent stabilizing
board 5 and the disk 1 and between the slider 7 and the disk 1 when
the disk 1 rotates. Thus, it is possible to more effectively
suppress fluttering of the disk 1 when the disk 1 is rotating, and
to stabilize rotation of the disk 1 at a position distanced from
the slider 7 and the transparent stabilizing board 5, which are
moved, for example, during the focus control.
[0129] Thus, in the focus control, because the rotation of the disk
1 is stabilized even at a distant position from the transparent
stabilizing board 5 and the slider 7, the disk 1 is less influenced
by the pressure fluctuation which may be caused, for example, when
the transparent stabilizing board 5 and the slider 7 are moved with
the optical pickup 4 to balance the air pressure between the disk 1
and the transparent stabilizing board 5 with that between the disk
1 and the slider 7. As a result, fluttering of the disk 1 is
suppressed more effectively. This brings stable and easy focus
control or tracking even when the biaxial actuator 14 using the
conventional servo technique is used, thus providing the recording
and reproducing device which can record and reproduce information
more stably and more desirably.
[0130] Note that, in order to create a space of reduced pressure
between the disk 1 and the stabilizing board 60 to attain stable
rotation of the disk 1, the distance between the disk 1 and the
stabilizing board 60 is preferably not less than 10 .mu.m and not
more than 200 .mu.m.
[0131] Further, the optical pickup 4 with the transparent
stabilizing board 5 provided below the disk 1 and the slider 7
provided above the disk 1 may be switched in their positions with
respect to the disk 1. In the case where the slider 7 is below the
disk 1 (on the side of the stabilizing board 60 of the disk 1), the
second opening 62 of the stabilizing board 60 makes up an opening
which is used to position the slider 7 in the vicinity of the disk
1.
[0132] Further, as shown in FIG. 8, the stabilizing board 60 may be
defined by an inner wall surface of a cartridge 80 which contains
the disk 1.
[0133] FIG. 8 is a cross sectional view showing a structure of
relevant part of the recording and reproducing device of FIG. 1,
when it is operated to record and reproduce information with
respect to the disk 1 contained in a disk cartridge 85. Here, the
disk cartridge 85 refers to the cartridge 80 containing the disk 1
therein. As shown in FIG. 8, the lower surface of the cartridge 80
(the surface of the cartridge 80 facing the disk 1 on the side of
the optical pickup 4) makes up a stabilizing section 80a which is
provided as the stabilizing board 60. That is, the lower surface of
the cartridge 80 serves as the stabilizing board 60. Note that, the
cross section of relevant part of the recording and reproducing
device shown in FIG. 8 is taken along the central line in the
radial direction of the disk 1 at a second opening 82 as shown in
FIG. 9.
[0134] The stabilizing section 80a has a first opening section 81
for chucking the center hub 2 of the disk 1 to the spindle 3, and
the second opening 82 which is used to position the optical pickup
4 with the transparent stabilizing board 5 in the vicinity of the
disk 1. Further, the upper surface of the cartridge 80 (the surface
of the cartridge 80 facing the disk 1 on the side of the slider 7)
has a third opening 83 which is used to position the slider 7 in
the vicinity of the disk 1 at a position opposite the second
opening 82.
[0135] Further, FIG. 9 is a plan view showing the cartridge 80 as
viewed from the side of the optical pickup 4, i.e., from below the
cartridge 80. As shown in FIG. 9, the cartridge 80 further includes
a slide shutter 84 which can be opened or closed in the directions
of arrows, capable of covering the first opening 81 and the second
opening 82. The slide shutter 84 is open when the first opening 81
and the second opening 82 are used during rotation of the disk 1,
whereas it is closed when the cartridge 80 containing the disk 1 is
taken out of the recording reproducing device.
[0136] Further, on the upper face of the cartridge 80 is provided a
slide shutter (not shown) for covering the third opening 83. This
slide shutter is also open when the third opening 83 is used,
whereas it is closed when the cartridge 80 containing the disk 1 is
taken out of the recording and reproducing device. This is to
protect the disk 1 from dusts.
[0137] The lower face of the cartridge 80 makes up the stabilizing
section 80a which serves as the stabilizing board 60. That is, one
of inner wall surfaces of the cartridge 80 makes up the stabilizing
board 60. Thus, a space of reduced pressure is created between the
disk 1 and the stabilizing section 80a when the disk 1 is rotating.
The disk 1, being flexible, is drawn to the stabilizing section 80a
and rotates at a constant distance from the stabilizing section
80a. This suppresses fluttering of the disk 1 further effectively
when the disk 1 is rotating, and rotation of the disk 1 can be
stabilized at a distant position from the slider 7 and the
transparent stabilizing board 5.
[0138] Thus, in the focus control, because the rotation of the disk
1 is stabilized even at a distant position from the transparent
stabilizing board 5 and the slider 7, the disk 1 is less influenced
by the pressure fluctuation which may be caused, for example, when
the transparent stabilizing board 5 and the slider 7 are moved with
the optical pickup 4 to balance the air pressure between the disk 1
and the transparent stabilizing board 5 with that between the disk
1 and the slider 7. As a result, fluttering of the disk 1 is
suppressed more effectively, thus providing the recording and
reproducing device which can record and reproduce information more
stably and more desirably.
[0139] Further, since the lower face of the cartridge 80 makes up
the stabilizing section 80a to serve as the stabilizing board 60,
rotation of the disk 1 can be stabilized without adding a new
member as the stabilizing board 60.
[0140] Note that, as in the foregoing example, the optical pickup 4
with the transparent stabilizing board 5 provided below the disk 1
and the slider 7 provided above the disk 1 may be switched in their
positions with respect to the disk 1. When the slider 7 is below
the disk 1 (on the side of he stabilizing board 80a), the second
opening 82 of the cartridge 80 becomes an opening which is used to
position the slider 7 in the vicinity of the disk 1, and the third
opening 83 becomes an opening which is used to position the optical
pickup 4 with the transparent stabilizing board 5 in the vicinity
of the disk 1.
[0141] Referring to FIG. 10, the following will describe a
recording and reproducing device in which the stabilizing board 60
is defined by the both inner wall surfaces of a cartridge 90
containing the disk 1.
[0142] The recording and reproducing device shown in FIG. 10 has
the same structure as that of FIG. 8 except for a disk cartridge
91, which is provided instead of the disk cartridge 85 to contain
the disk 1.
[0143] As with the cartridge 80, the lower face of the cartridge 90
has the stabilizing section 80a as shown in FIG. 9, as well as the
first opening 81, the second opening 82, the third opening 83, and
the slide shutter 84. Further, as with the cartridge 80, the upper
face of the cartridge 90 has a slide shutter (not shown) covering
the third opening 83. This protects the disk 1 from dusts.
[0144] Further, the cartridge 90 differs from the cartridge 80 of
FIG. 8 in that the width of the cartridge 90 across the surface of
the cartridge 90 facing the disk 1 on the side of the slider 7
(hereinafter referred to as upper surface of the cartridge 90) and
the surface of the cartridge 90 facing the disk 1 on the side of
the optical pickup 4 (hereinafter referred to as lower surface of
the cartridge 90), i.e., a distance between the inner wall surfaces
of the cartridge 90 centered by the disk 1, is restricted within
such a range which enables the cartridge 90 to serve as the
stabilizing board 60.
[0145] That is, in order for the upper and lower surfaces of the
cartridge 90 respectively facing the disk 1 to serve as the
stabilizing board 60, the upper and lower surfaces of the cartridge
90 need to be positioned in such a manner that a space of reduced
pressure is created above and below the disk 1 between the upper
and lower surfaces of the cartridge 90.
[0146] Specifically, it is preferable that the distance between the
disk 1 and the upper surface of the cartridge 90 and the distance
between the disk 1 and the lower surface of the cartridge 90 are
each not less than 10 .mu.m and not more than 200 .mu.m.
[0147] A distance of not less than 10 .mu.m between the disk 1 and
each surface of the cartridge 90 facing the disk 1 prevents a
collision between the disk 1 and the cartridge 90, which may be
caused by external influence such as oscillation, and thus prevents
the disk 1 from being scratched.
[0148] Further, a distance of not more than 200 .mu.m between the
disk 1 and each surface of the cartridge 90 facing the disk 1 makes
the disk 1 less susceptible to external influence such as
oscillation. That is, because the space inside the cartridge 90 is
restricted, the influence of external oscillation on the state of
reduced pressure between the disk 1 and the upper and lower
surfaces of the cartridge 90 becomes less. Thus, it is possible to
suppress fluttering of the disk 1 in the cartridge 90, which is
caused when rotation of the disk 1 in the cartridge 90 becomes
instable in response to external force, for example, by
oscillation. As a result, rotation of the disk 1 can be
stabilized.
[0149] The foregoing restriction of the space within the cartridge
90 enables the upper and lower surfaces of the cartridge 90
respectively facing the disk 1 to function as the stabilizing board
60. That is, the state of reduced pressure between the disk 1 and
the cartridge 90 is stabilized, and the disk 1 becomes less
susceptible to external influence such as oscillation. This
prevents fluttering of the disk 1 in the cartridge 90, thus stably
rotating the disk 1. Further, the disk 1 is prevented from
colliding with the upper or lower surface of the cartridge 90, thus
preventing a scratch on a surface of the disk 1.
[0150] Thus, the recording and reproducing device provided with the
cartridge 90 can stabilize rotation of the disk 1 at a distant
position from the slider 7 and the transparent stabilizing board 5,
when, for example, the transparent stabilizing board 5 and the
slider 7 are moved with the optical pickup 4. As a result,
recording and reproducing can be carried out more stably and more
desirably.
[0151] Further, since the stabilizing board 60 is defined by the
upper and lower surfaces of the cartridge 90, rotation of the disk
1 can be stabilized more effectively without introducing a new
member as the second stabilizing board 60.
[0152] Further, the stable rotation of the disk 1 allows the use of
a thinner disk for the disk 1. Here, in order for the disk 1 to be
effectively flexible, the thickness of the disk 1 is preferably not
less than 30 .mu.m and not more than 400 .mu.m. Since the disk 1 is
flexible, a thickness less than 30 .mu.m makes it difficult to
maintain sufficient strength for the disk 1 to withstand rotation.
On the other hand, a thickness of the disk 1 exceeding 400 .mu.m
makes the disk 1 less flexible, which prevents the disk 1 from
being drawn to the stabilizing section 80a even with the presence
of a space of reduced pressure between the disk 1 and the
stabilizing section 80a. As a result, the effect of suppressing
fluttering of the disk 1 becomes less effective.
[0153] According to the foregoing First and Second Embodiments, a
recording and reproducing device of the present invention includes
a light source, focusing means for converging and projecting a
laser beam which was emitted from the light source on a disk, and
rotation driving means for rotating the disk, the recording and
reproducing device comprising: a first stabilizing board, provided
between the disk and the focusing means, which is moved with the
focusing means, for example, such as an objective lens; and a
slider which is disposed to face the first stabilizing board via
the disk and supported to oscillate, a surface of the slider facing
the disk being flat.
[0154] According to this arrangement, when recording or reproducing
information with respect to the disk, i.e., when rotating the disk,
the rotation of the disk causes air to flow into the space between
the disk and the slider, which increases the air pressure between
the disk and the slider because the surface of the slider facing
the disk is flat. That is, pressure is created between the disk and
the slider. In the same manner, the rotation of the disk causes air
to flow into the space between the disk and the first stabilizing
board, which creates pressure between the disk and the first
stabilizing board. Further, the slider is supported to oscillate.
This enables the slider to move to such a position that the air
pressure between the disk and the first stabilizing board and that
between the slider and the disk balance out.
[0155] Balancing the pressure between the slider and the disk with
that between the first stabilizing board and the disk in this
manner enables the disk to rotate at a constant distance from the
slider and the first stabilizing board. As a result, fluttering of
the rotating disk can be suppressed, thus stabilizing rotation of
the disk.
[0156] If it is assumed here that the first stabilizing board is
not provided and the disk and the focusing means are disposed face
to face with nothing in between, the focusing means, when it is
driven on the optical pickup for example, makes up the surface of
the optical pickup facing the disk. Therefore, this surface of the
optical pickup has relatively large irregularities. The result of
this is that the pressure around the focusing means fluctuates
every time the focusing means is moved, which easily changes the
air pressure between the focusing means and the disk. Thus, the
disk flutters when the focusing means is moved.
[0157] However, by providing the first stabilizing board which
moves with the focusing means between the disk and the focusing
means, the surface on the side of the focusing means facing the
disk becomes flat, which creates uniform air pressure between this
flat surface and the disk. As a result, it is possible to suppress
fluctuation of air pressure between the first stabilizing board and
the disk and thus fluttering of the disk, for example, even when
the focusing means is moved to carry out a focus control.
[0158] Further, because the slider is supported to oscillate in a
vertical direction with respect to the disk, the air pressure
between the disk and the slider can be changed so that the air
pressure between the disk and the first stabilizing board is
balanced with that between the disk and the slider, even when the
air pressure between the disk and the first stabilizing board is
caused to fluctuate, for example, by the movement of the optical
pickup with the focusing means during a focus control.
[0159] Thus, even when the focusing means and thus the first
stabilizing board is moved relative to the disk, the movement is
accompanied by the movement of the slider relative to the disk, so
as to balance the air pressure between the disk and the first
stabilizing board with that between the disk and the slider. The
air pressure can be balanced easily and stably because the surface
of the slider facing the disk is also flat. As a result, it is
possible to suppress vertical displacement of the disk, i.e.,
fluttering of the disk, which is caused by fluctuation of pressure
around the disk, thus stably and easily carrying out a focus
control and tracking, for example.
[0160] Thus, the disk can be stably rotated even when the focusing
means or the optical pickup with the focusing means is moved,
thereby providing a recording and reproducing device which can
record and reproduce information stably and desirably even with a
thin disk. Further, the use of a thin disk means a shorter optical
path in the disk, which makes it possible to provide a large margin
of error for a tilt of the disk. As a result, recording density of
the disk can be increased.
[0161] It is preferable in the recording and reproducing device
that the first stabilizing board is fixed to the focusing means via
an elastic member having elasticity.
[0162] According to this arrangement, even when the slider
oscillates due to external force and the disk is oscillated by the
pressure created between the disk and the slider, the elastic
member stretches or compresses to enable the first stabilizing
board to follow the oscillating disk, so as to balance the air
pressure between the disk and the first stabilizing board with that
between the disk and the slider. As a result, it is possible to
prevent damage to the disk, which is caused when the disk collides
with the first stabilizing board in response to external
oscillation.
[0163] In the recording and reproducing device, it is preferable
that the focusing means is a complex lens composed of at least two
lenses.
[0164] This arrangement makes it possible to increase numerical
aperture NA of the focusing means, and thus to reduce the spot size
of a laser beam projected on the disk. As a result, recording
capacity of the disk, and thus recording density of the disk can be
increased, thus providing a recording and reproducing device which
is suitable for high-density recording and reproducing.
[0165] In the recording and reproducing device, it is preferable
that the slider includes a magnetic field generating element for
generating a magnetic field.
[0166] According to this arrangement, the slider with a magnetic
field generating element makes it possible to provide a recording
and reproducing device which can record and reproduce information
using a magneto-optical disk incorporating a recording medium which
requires a magnetic field for recording.
[0167] It is preferable in the recording and reproducing device
that the first stabilizing board is transparent.
[0168] According to this arrangement, since the first stabilizing
board is transparent, a laser beam emitted from the light source
can pass through the first stabilizing board without providing, for
example, an opening in the first stabilizing board for passing the
laser beam, even though the first stabilizing board is provided
between the disk and the focusing means.
[0169] It is preferable that the recording and reproducing device
further includes a second stabilizing board which is disposed to
face the disk and to create a space of reduced pressure between the
disk and the second stabilizing board when the disk is rotating.
Note that, the second stabilizing board may be provided to face
either side of the disk.
[0170] According to this arrangement, since the second stabilizing
board is separately provided from the slider in the vicinity of the
disk and opposite the disk, rotation of the disk can create a space
of reduced pressure between the disk and the second stabilizing
board. Here, the disk is drawn toward the second stabilizing board
and rotates at a constant distance from the second stabilizing
board, thereby suppressing fluttering of the disk and stabilizing
rotation of the disk even at a location where the disk is distanced
from the slider or the first stabilizing board.
[0171] Thus, the disk stably rotates even at a distant position
from the first stabilizing board or slider, despite that the first
stabilizing board and the slider are moved to balance the air
pressure between the disk and the first stabilizing board with that
between the disk and the slider, for example, in response to the
movement of the optical pickup with the focusing means. Thus, the
disk is not influenced by the pressure fluctuation which is caused
by the movement of the first stabilizing board and the slider, thus
suppressing fluttering of the disk more effectively. As a result,
it is possible to provide a recording and reproducing device which
can record and reproduce information more stably and more
desirably.
[0172] It is preferable in the recording and reproducing device
that the second stabilizing board has an opening which is used to
position the slider or the first stabilizing board in the vicinity
of the disk when recording or reproducing information.
[0173] According to this arrangement, since the slider or the first
stabilizing board can be positioned in the vicinity of the disk
during recording or reproducing, the pressure between the disk and
the slider and the pressure between the disk and the first
stabilizing board can be balanced more stably.
[0174] In a disk cartridge of the present invention which contains
a disk in a cartridge used in the recording and reproducing device,
the disk being exposed from the disk cartridge when recording or
reproducing information, one of inner wall surfaces of the
cartridge defines the second stabilizing board of the disk.
[0175] According to this arrangement, since the second stabilizing
board is defined by one of inner wall surfaces of the cartridge, a
space of reduced pressure is created between the disk and this
inner wall surface during rotation of the disk. Here, the disk is
drawn toward the inner wall surface of the cartridge and rotates at
a constant distance from this inner wall surface. As a result,
fluttering of the disk can be suppressed, and the disk can be
rotated more stably at a position distanced from the slider and the
first stabilizing board.
[0176] Thus, the disk stably rotates even at a position distanced
from the first stabilizing board or slider, despite that the first
stabilizing board and the slider are moved to balance the air
pressure between the disk and the first stabilizing board with that
between the disk and the slider, for example, in response to the
movement of the optical pickup with the focusing means. Thus, the
disk is not influenced by the pressure fluctuation which is caused
by the movement of the first stabilizing board and the slider, thus
suppressing fluttering of the disk more effectively. As a result,
it is possible to provide a recording and reproducing device which
can record and reproduce information more stably and more
desirably.
[0177] Further, since the second stabilizing board is defined by
one of inner wall surfaces of the cartridge, the second stabilizing
board, for stabilizing rotation of the disk, can be provided
without introducing an additional member.
[0178] In a disk cartridge of the present invention which contains
a disk in a cartridge, the disk being exposed from the cartridge
when recording or reproducing information, the cartridge has inner
wall surfaces which define a second stabilizing board which is
disposed to face the disk and to create a space of reduced pressure
between the disk and the second stabilizing board when the disk is
rotating.
[0179] According to this arrangement, since the second stabilizing
board is defined by the both inner wall surfaces of the cartridge,
a space of reduced pressure is created between the disk and the
both inner wall surfaces of the cartridge during rotation of the
disk. Here, the disk rotates at a constant distance from the both
inner wall surfaces of the cartridge, thus suppressing fluttering
of the disk.
[0180] Further, since the second stabilizing board is defined by
the both inner wall surfaces of the cartridge, the second
stabilizing board, for stabilizing rotation of the disk, can be
provided without introducing an additional member.
[0181] Specifically, it is preferable that a distance between the
disk and each inner wall surface of the disk cartridge is not less
than 10 .mu.m and not more than 200 .mu.m.
[0182] According to this arrangement, by the distance between the
disk and each inner wall surface of the cartridge not less than 10
.mu.m, the disk is prevented from colliding with the cartridge in
response to external influence such as oscillation, thus preventing
a scratch on the disk.
[0183] Further, by the distance between the disk and each inner
wall surface of the cartridge not more than 200 .mu.m, the disk
becomes less susceptible to external influence such as oscillation.
That is, since the space inside the cartridge is restricted, there
is less pressure fluctuation in the cartridge. Therefore, the space
of reduced pressure between the disk and the inner wall surfaces of
the cartridge will not be interfered even in the presence of
external oscillation. Thus, rotation of the disk in the cartridge
will not become instable even in the presence of external influence
such as oscillation, thus preventing fluttering of the disk in the
cartridge. In effect, rotation of the disk can be stabilized.
[0184] It is preferable in the disk cartridge that the inner wall
surfaces of the cartridge have an opening through which the disk is
exposed when recording or reproducing information, and which is
used to position a first stabilizing board and a slider in a
vicinity of the disk, the first stabilizing board being disposed
between focusing means the disk used in a recording and reproducing
device, the first stabilizing board being moved with the focusing
means, and the slider being disposed to face the first stabilizing
board via the disk and supported to oscillate, a surface of the
slider facing the first stabilizing board being flat.
[0185] According to this arrangement, the opening on the both inner
wall surfaces of the cartridge can be used to position the slider
and the first stabilizing board in the vicinity of the disk.
Further, during rotation of the disk, air flows in between the disk
and the slider and between the disk and the first stabilizing
board, which creates a space of reduced pressure between the disk
and the slider and between the disk and the first stabilizing
board. Thus, because the first stabilizing board and the slider for
balancing the pressure to stably rotate the disk are positioned in
the vicinity of the disk, the pressure between the disk and the
slider and the pressure between the disk and the first stabilizing
board can be balanced more stably.
[0186] The present invention is applicable to any disk,
irrespective of whether the disk is flexible or not. However, the
present invention is especially effective for a flexible optical
disk. That is, in view of the fact that a flexible disk is more
likely to flutter than an inflexible disk at the same rotational
speed, the present invention, which is intended to suppress
fluttering of the disk during rotation, can be more effectively
used for a flexible disk which easily flutters.
[0187] [Third Embodiment]
[0188] The following will describe yet another embodiment of the
present invention. Note that, constituting elements having the same
functions as those described in the foregoing First and Second
Embodiments are given the same reference numerals and explanations
thereof are omitted here.
[0189] As shown in FIG. 11, a recording and reproducing device
according to the present embodiment has the same structure as that
of the recording and reproducing device as shown in FIG. 2 of the
First Embodiment, except for the transparent stabilizing board 5
(first stabilizing board 5), which is slightly modified in this
embodiment.
[0190] A first stabilizing board 5 of the present embodiment has an
opening 5a in an optical path of a laser beam 11, as shown in FIG.
11, so that the laser beam 11 can pass through it. The laser beam
11 emitted from an light emitting and detecting optical system 10
to irradiate a disk 1, or reflected at the disk 1 travels through
the opening 5a.
[0191] In this manner, by providing the first stabilizing board 5
with the opening 5a which passes the laser beam 11 in the optical
path of the laser beam 11, the material of the first stabilizing
board 5 will not be limited to those which pass the laser beam 11,
e.g., a transparent material, and a non-transparent material may be
used. That is, a range of materials of the first stabilizing board
5 will not be limited, allowing the first stabilizing board 5 to be
made from a material having good workability and good
durability.
[0192] Further, by the provision of the opening 5a in the first
stabilizing board 5, the laser beam 11 can travel through the
opening 5a without reflecting at the surface of the first
stabilizing board 5. Thus, the laser beam 11 can be used more
efficiently. For example, compared with the case where the first
stabilizing board 5 is not provided with the opening 5a and the
laser beam 11 partially reflects at the surface of the first
stabilizing board 5, information can be recorded and reproduced at
lower power, thus reducing power consumption of the recording and
reproducing device.
[0193] Further, the shape of the opening 5a is not particularly
limited as long as it can pass the laser beam 11, and it may be,
for example, in the form of a cylinder. However, as shown in FIG.
12, the opening 5a is preferably in the form of a bowl on the
optical path of the laser beam 11 travelling through the first
stabilizing board 5.
[0194] The bowl shape of the opening 5a on the optical path of the
laser beam 11 travelling through the first stabilizing board 5
decreases the area of the opening 5a facing the disk 1, without
blocking the laser beam 11 by the first stabilizing board 5. This
suppresses air turbulence which may be caused at the opening 5a
when the disk 1 is rotated, thereby suppressing disturbance of air
pressure between the disk 1 and the first stabilizing board 5. As a
result, it is possible to suppress fluttering of the disk 1 and
stabilize rotation of the disk 1.
[0195] Note that, the disk 1 is not just limited to the optic disk,
and, for example, a magneto-optical disk which employs a
magneto-optical recording medium as the recording medium 1b may be
used as well.
[0196] Referring to FIG. 13, the following describes an example of
the recording and reproducing device which records and reproduces
information using a magneto-optical disk as the disk 1. Recording
of information on the magneto-optical disk requires a recording
magnetic field. A recording magnetic field is applied to an area
where the laser beam 11 is focused on. This is attained by a
magnetic head (magnetic field generating element) 40 embedded in a
slider 7. The structure other than the integral structure of the
magnetic head 40 in the slider 7 is the same as that shown in FIG.
11.
[0197] To record information in the disk 1, the laser beam 11
irradiated on the disk 1 raises the temperature of the recording
medium 1b of a disk substrate 1a to reduce coercive force of the
recording medium 1b. Here, the magnetic head 40 generates a
magnetic field which is applied to the disk 1.
[0198] In the optical pickup 4, the laser beam 11 emitted from the
light emitting and detecting optical system 10 is converged by the
objective lens 12 to irradiate the disk 1. By the reduced coercive
force of the disk 1 and the applied magnetic field from the
magnetic head 40, the magnetization direction of the disk 1 becomes
different. Here, the magnetic head 40 and the optical pickup 4 are
moved together. That is, information is recorded in the disk 1.
[0199] By thus providing the slider 7 with the magnetic head 40, it
is possible to realize a recording and reproducing device which can
record and reproduce information using a magneto-optical disk with
a recording medium which requires a recording magnetic field.
[0200] As with the structure of FIG. 11, the structure as shown in
FIG. 13 also includes the first stabilizing board 5, and the slider
7 which is provided opposite the first stabilizing board 5 via the
disk 1. This structure suppresses pressure fluctuation around the
disk 1 and the optical pickup 4 and thus stabilizes rotation of the
disk 1 even when the objective lens 12 or the optical pickup 4
provided with the objective lens 12 is moved, thereby providing a
recording and reproducing device which can record and reproduce
information stably and desirably even when a thin disk is used for
the disk 1. Further, since the first stabilizing board 5 has the
opening 5a in the form of a bowl, the laser beam 11 can be used
efficiently. In addition, disturbance of air pressure between the
disk 1 and the first stabilizing board 5 can be suppressed. As a
result, rotation of the disk 1 can be stabilized.
[0201] Further, the objective lens 12 is not just limited to the
simple lens as shown in FIG. 11, and it may be a complex lens
combining at least two lenses. For example, FIG. 14 shows an
exemplary structure of the objective lens 12 using a dual lens,
which is a combination of two lenses, in the recording and
reproducing device as shown in FIG. 1 of the First Embodiment.
[0202] The dual lens which is provided as the objective lens 12 is
composed of a lens 50 and a lens 51. This arrangement enables
numerical aperture NA of the objective lens 12 to be increased.
Specifically, with the use of the dual lens, the numerical aperture
NA of the objective lens 12 can be increased to 0.7 or greater, or
more preferably around 0.8 to 0.95. As a result, the laser beam 11
projected on the disk 1 can have a smaller spot size, which
increases the recording capacity and thus density of the disk 1.
The end result of this is the recording and reproducing device
which is suitable for high density recording and reproducing.
[0203] The numerical aperture NA can also be increased when a
simple lens is used for the objective lens 12, but manufacture of
the objective lens 12 with larger numerical aperture NA is easier
when the dual lens is used. Therefore, in order to have numerical
aperture NA of 0.7 or greater as in this embodiment, it is
preferable to use a dual lens for the objective lens 12.
[0204] Note that, the exemplary structure as shown in FIG. 14 which
incorporates the magnetic head 40 and uses the magneto-optical disk
as the disk 1 can also use an optic disk. In this case, the
magnetic head 40 will not be required.
[0205] Further, as shown in FIG. 15, the first stabilizing board 15
may be fixed on the optical pickup 4 via the board spring 60
(elastic member). FIG. 15 shows a structure which incorporates the
board spring 60 between the first stabilizing board 5 and the
optical pickup 4 in the structure of the recording and reproducing
device shown in FIG. 13.
[0206] As shown in FIG. 15, the transparent stabilizing board 5 is
fixed on the optical pickup casing 15 via the board spring 60.
According to the structure of FIG. 15, even when the slider 7
oscillates in response to external oscillation and the disk 1
oscillates by the pressure between the disk 1 and the slider 7 in
response to this oscillation of the slider 7, the transparent
stabilizing board 5 can follow the oscillation of the disk 1 by the
stretch and compression of the board spring 60 to balance the air
pressure between the disk 1 and the transparent stabilizing board 5
with that between the disk 1 and the slider 7.
[0207] Thus, it is possible to prevent damage to the disk 1 which
may be caused when the disk 1 collides with the transparent
stabilizing board 5 in response to external oscillation.
[0208] Note that, the board spring 60 is not just limited to a
spring as long as it is elastic. For example, materials such as
rubber or foamed resin may be used instead. Here, as the term is
used, "spring" may be any elastic body. The spring is preferable
because it has a large stroke in response to a load.
[0209] [Fourth Embodiment]
[0210] The following will describe yet another embodiment of the
present invention. Note that, constituting elements having the same
functions as those described in the foregoing embodiments are given
the same reference numerals and explanations thereof are omitted
here.
[0211] FIG. 16 is a cross sectional view showing a relevant portion
of a recording and reproducing device according to the present
embodiment, in which a second stabilizing board 70 is added to the
structure of FIG. 1 according to the First Embodiment. FIG. 17 is a
plan view of the second stabilizing board 70. Note that, the cross
section of FIG. 16 showing a relevant portion of the recording and
reproducing device is taken along the central line in the radial
direction of the second stabilizing board 70 at a second opening
72.
[0212] The second stabilizing board 70 is larger than a first
stabilizing board 5, and, for example, in the form of a circle
slightly larger than the disk 1, as shown in FIG. 17. Further, the
second stabilizing board 70 has a first opening 71 for chucking a
center hub 2 of the disk 1 to a spindle 3, and the second opening
72 which is used to position an optical pickup 4 with the first
stabilizing board 5 in the vicinity of the disk 1. Further, the
second stabilizing board 70 in the recording and reproducing device
is fixed at such a position that it is opposite the disk 1 and can
create a space of reduced pressure between the disk 1 and the
second stabilizing board 70 during rotation of the disk 1.
[0213] By thus providing the second stabilizing board 70 larger
than and separately from the slider 7 and the first stabilizing
board 5 at a position opposite and in the vicinity of the disk 1, a
space of reduced pressure can be created between the disk 1 and the
second stabilizing board 70 during rotation of the disk 1. Here,
the disk 1, being flexible, is drawn to the second stabilizing
board 70 and rotates at a constant distance from the second
stabilizing board 70. Thus, the addition of the second stabilizing
board 70 can further stabilize rotation of the disk 1, compared
with the case where rotation of the disk 1 is stabilized by
providing only the first stabilizing board 5 and the slider 7 which
are moved with the optical pickup 4. Thus, it is possible to more
effectively prevent fluttering of the disk 1 when the disk 1 is
rotating, and to stabilize rotation of the disk 1 at a distant
position from the slider 7 and the first stabilizing board 5.
[0214] Thus, in the focus control, because the rotation of the disk
1 is stabilized even at a distant position from the transparent
stabilizing board 5 and the slider 7, the disk 1 is less influenced
by the pressure fluctuation which may be caused, for example, when
the transparent stabilizing board 5 and the slider 7 are moved with
the optical pickup 4 to balance the air pressure between the disk 1
and the transparent stabilizing board 5 with that between the disk
1 and the slider 7. As a result, fluttering of the disk 1 is
suppressed more effectively. This brings stable and easy focus
control or tracking even when the biaxial actuator 14 using the
conventional servo technique is used, thus providing the recording
and reproducing device which can record and reproduce information
more stably and more desirably.
[0215] Note that, in order to create a space of reduced pressure
between the disk 1 and the second stabilizing board 70 to attain
stable rotation of the disk 1, the distance between the disk 1 and
the second stabilizing board 70 is preferably not less than 10
.mu.m and not more than 200 .mu.m.
[0216] Further, the optical pickup 4 with the transparent
stabilizing board 5 provided below the disk 1 and the slider 7
provided above the disk 1 may be switched in their positions with
respect to the disk 1. In the case where the slider 7 is below the
disk 1 (on the side of the second stabilizing board 70 of the disk
1), the second opening 72 of the second stabilizing board 70 makes
up an opening which is used to position the slider 7 in the
vicinity of the disk 1.
[0217] Further, as shown in FIG. 18, the second stabilizing board
70 may be defined by an inner wall surface of a cartridge 90 which
contains the disk 1.
[0218] FIG. 18 is a cross sectional view showing a structure of
relevant part of the recording and reproducing device of FIG. 1
according to the First Embodiment, when it is operated to record
and reproduce information with respect to the disk 1 contained in a
disk cartridge 95. Here, the disk cartridge 95 refers to the
cartridge 90 containing the disk 1. As shown in FIG. 18, the lower
surface of the cartridge 90 (the surface of the cartridge 90 facing
the disk 1 on the side of the optical pickup 4) makes up a
stabilizing section 90a which is provided as the second stabilizing
board 7b. That is, the lower surface of the cartridge 90 serves as
the second stabilizing board 70. Note that, the cross section of
relevant part of the recording and reproducing device of FIG. 18 is
taken along the central line in the radial direction of the disk 1
at a second opening 92 as shown in FIG. 19.
[0219] The stabilizing section 90a has a first opening section 91
for chucking the center hub 2 of the disk 1 to the spindle 3, and
the second opening 92 which is used to position the optical pickup
4 with the transparent stabilizing board 5 in the vicinity of the
disk 1. Further, the upper surface of the cartridge 90 (the surface
of the cartridge 90 facing the disk 1 on the side of the slider 7)
has a third opening 93 which is used to position the slider 7 in
the vicinity of the disk 1 at a position opposite the second
opening 92.
[0220] Further, FIG. 19 is a plan view showing the cartridge 90 as
viewed from the side of the optical pickup 4, i.e., from below the
cartridge 90. As shown in FIG. 19, the cartridge 90 further
includes a slide shutter 94 which can be opened or closed in the
directions of arrows, capable of covering the first opening 91 and
the second opening 92. The slide shutter 94 is open when the first
opening 91 and the second opening 92 are used while the disk 1 is
rotating, whereas it is closed when the cartridge 90 containing the
disk 1 is taken out of the recording reproducing device.
[0221] Further, on the upper face of the cartridge 90 is provided a
slide shutter (not shown) for covering the third opening 93. The
slide shutter is open when the third opening 93 is used, whereas it
is closed when the cartridge 90 storing the disk 1 is taken out of
the recording and reproducing device. This is to protect the disk 1
from dusts.
[0222] The lower face of the cartridge 90 makes up the stabilizing
section 90a which serves as the second stabilizing board 70. That
is, one of inner wall surfaces of the cartridge 90 makes up the
second stabilizing board 70. Thus, a space of reduced pressure is
created between the disk 1 and the stabilizing section 90a when the
disk 1 is rotating. The disk 1, being flexible, is drawn to the
stabilizing section 90a and rotates at a constant distance from the
stabilizing section 90a. This suppresses fluttering of the disk 1
further effectively when the disk 1 is rotating, and rotation of
the disk 1 can be stabilized at a distance position from the slider
7 and the first stabilizing board 5.
[0223] Thus, because the rotation of the disk 1 is stabilized even
at a distant position from the transparent stabilizing board 5 and
the slider 7, the disk 1 is less influenced by the pressure
fluctuation which may be caused, for example, when the transparent
stabilizing board 5 and the slider 7 are moved with the optical
pickup 4 to balance the air pressure between the disk 1 and the
transparent stabilizing board 5 with that between the disk 1 and
the slider 7. As a result, fluttering of the disk 1 is suppressed
more effectively, thus providing the recording and reproducing
device which can record and reproduce information more stably and
more desirably.
[0224] Further, since the lower face of the cartridge 90 makes up
the stabilizing section 90a to serve as the second stabilizing
board 70, rotation of the disk 1 can be stabilized without adding a
new member as the second stabilizing board 70.
[0225] Note that, as in the foregoing example, the optical pickup 4
with the first stabilizing board 5 provided below the disk 1 and
the slider 7 provided above the disk 1 may be switched in their
positions with respect to the disk 1. When the slider 7 is below
the disk 1 (on the side of he stabilizing board 90a), the second
opening 92 of the cartridge 90 becomes an opening which is used to
position the slider 7 in the vicinity of the disk 1, and the third
opening 93 becomes an opening which is used to position the optical
pickup 4 with the first stabilizing board 5 in the vicinity of the
disk 1.
[0226] Referring to FIG. 20, the following will describe a
recording and reproducing device in which the second stabilizing
board 70 is defined by the both inner wall surfaces of a cartridge
96 containing the disk 1.
[0227] The recording and reproducing device as shown in FIG. 20 has
the same structure as that of FIG. 18 except that a disk cartridge
97 is provided instead of the disk cartridge 95 to contain the disk
1 in the cartridge 96.
[0228] As with the cartridge 90, the lower face of the cartridge 96
has the stabilizing section 90a as shown in FIG. 19, as well as the
first opening 91, the second opening 92, the third opening 93, and
the slide shutter 94. Further, as with the cartridge 90, the upper
face of the cartridge 96 has a slide shutter (not shown) covering
the third opening 93. This protects the disk 1 from dusts.
[0229] Further, the cartridge 96 differs from the cartridge 90 of
FIG. 18 in that the width of the cartridge 96 across the surface of
the cartridge 96 facing the disk 1 on the side of the slider 7
(hereinafter referred to as upper surface of the cartridge 96) and
the surface of the cartridge 96 facing the disk 1 on the side of
the optical pickup 4 (hereinafter referred to as lower surface of
the cartridge 96), i.e., a distance between the inner wall surfaces
of the cartridge 96 centered by the disk 1, is restricted within
such a range which enables the cartridge 96 to serve as the second
stabilizing board 70.
[0230] That is, in order for the upper and lower surfaces of the
cartridge 96 facing the disk 1 to serve as the second stabilizing
board 70, the upper and lower surfaces of the cartridge 96 need to
be positioned in such a manner that a space of reduced pressure is
created above and below the disk 1 between the upper and lower
surfaces of the cartridge 96.
[0231] Specifically, it is preferable that the distance between the
disk 1 and the upper surface of the cartridge 96, and the distance
between the disk 1 and the lower surface of the cartridge 96 are
each not less than 10 .mu.m and not more than 200 .mu.m.
[0232] A distance of not less than 10 .mu.m between the disk 1 and
each surface of the cartridge 96 facing the disk 1 prevents a
collision between the disk 1 and the cartridge 96 which may be
caused by external influence such as oscillation, and thus prevents
the disk 1 from being scratched.
[0233] Further, a distance of not more than 200 .mu.m between the
disk 1 and each surface of the cartridge 96 facing the disk 1 makes
the disk 1 less susceptible to external influence such as
oscillation. That is, because the space inside the cartridge 96 is
restricted, the influence of external oscillation on the state of
reduced pressure between the disk 1 and the upper and lower
surfaces of the cartridge 96 becomes less. Thus, it is possible to
suppress fluttering of the disk 1 in the cartridge 96, which is
caused when rotation of the disk 1 in the cartridge 96 becomes
instable in response to external force, for example, by
oscillation. As a result, rotation of the disk 1 can be
stabilized.
[0234] The foregoing restriction of the space within the cartridge
96 enables the upper and lower surfaces of the cartridge 96 facing
the disk 1 to function as the second stabilizing board 70. That is,
the state of reduced pressure between the disk 1 and the cartridge
96 is stabilized, and the disk 1 becomes less susceptible to
external influence such as oscillation. This prevents fluttering of
the disk 1 in the space of the cartridge 96, and the disk 1 can be
rotated stably. Furthers the disk 1 is prevented from colliding
with the upper or lower surface of the cartridge 96, thus
preventing a scratch on the surfaces of the disk 1.
[0235] Thus, the recording and reproducing device provided with the
cartridge 96 can stabilize rotation of the disk 1 at a distant
position from the slider 7 and the first stabilizing board 5, when,
for example, the first stabilizing board 5 and the slider 7 are
moved with the optical pickup 4. As a result, recording and
reproducing can be carried out more stably and more desirably.
[0236] Further, since the second stabilizing board 70 is defined by
the upper and lower surfaces of the cartridge 96, rotation of the
disk 1 can be stabilized more effectively without introducing a new
member as the second stabilizing board 70.
[0237] Further, the stable rotation of the disk 1 allows the use of
a thinner disk for the disk 1. Here, in order for the disk 1 to be
effectively flexible, the thickness of the disk 1 is preferably not
less than 30 .mu.m and not more than 400 .mu.m. Since the disk 1 is
flexible, a thickness less than 30 .mu.m makes it difficult to
maintain sufficient strength for the disk 1 to withstand rotation.
On the other hand, a thickness of the disk 1 exceeding 400 .mu.m
makes the disk 1 less flexible, which prevents the disk 1 from
being drawn to the stabilizing section 90a even when a space of
reduced pressure is created between the disk 1 and the stabilizing
section 90a. As a result, the effect of suppressing fluttering of
the disk 1 when it is rotating becomes less effective.
[0238] According to the foregoing Third and Fourth Embodiments, a
recording and reproducing device of the present invention includes
a light source, focusing means for converging and projecting a
laser beam which was emitted from the light source on a disk, and
rotation driving means for rotating the disk, the recording and
reproducing device comprising: a first stabilizing board, provided
between the disk and the focusing means, which is moved with the
focusing means; and a slider which is disposed to face the first
stabilizing board via the disk and supported to oscillate, a
surface of the slider facing the disk being flat, wherein the first
stabilizing board has an opening in an optical path of the laser
beam so as to allow passage of the laser beam.
[0239] According to this arrangement, when recording or reproducing
information with respect to the disk, i.e., during rotation of the
disk, the rotation of the disk induces an air flow between the disk
and the slider, and the air pressure between the slider and the
disk increases because the surface of the slider facing the disk is
flat. That is, pressure is created between the slider and the disk.
In the same manner, the rotation of the disk also induces an air
flow between the disk and the first stabilizing board to create
pressure therebetween. In addition, the slider is supported to
oscillate. This enables the slider to be moved to balance the air
pressure between the disk and the first stabilizing board and that
between the slider and the disk.
[0240] By this pressure-induced state and balancing of it between
(1) the slider and the disk and (2) the first stabilizing board and
the disk, the disk rotates at a constant distance from the slider
and the first stabilizing board. This suppresses fluttering of the
disk when it is rotating, and thus stabilizes the rotation of the
disk.
[0241] If it is assumed here that the first stabilizing board is
not provided and the disk and the focusing means are disposed face
to face with nothing in between, the focusing means, when it is
driven on the optical pickup for example, makes up the surface of
the optical pickup facing the disk. Therefore, this surface of the
optical pickup has relatively large irregularities. The result of
this is that the pressure around the focusing means fluctuates
every time the focusing means is moved, which easily changes the
air pressure between the focusing means and the disk. Thus, the
disk flutters when the focusing means is moved.
[0242] However, by providing the first stabilizing board which
moves with the focusing means between the disk and the focusing
means, the surface on the side of the focusing means facing the
disk becomes flat, which creates uniform air pressure between this
flat surface and the disk. As a result, it is possible to suppress
fluctuation of air pressure between the first stabilizing board and
the disk and thus fluttering of the disk, for example, even when
the focusing means is moved to carry out a focus control.
[0243] Further, because the slider is supported to oscillate in a
vertical direction with respect to the disk, the air pressure
between the disk and the slider can be changed so that the air
pressure between the disk and the first stabilizing board is
balanced with that between the disk and the slider, even when the
air pressure between the disk and the first stabilizing board is
caused to fluctuate, for example, by the movement of the optical
pickup with the focusing means during a focus control.
[0244] Thus, even when the focusing means and thus the first
stabilizing board is moved with respect to the disk, the movement
is accompanied by the movement of the slider relative to the disk,
so as to balance the air pressure between the disk and the first
stabilizing board with that between the disk and the slider. The
air pressure can be balanced easily and stably because the surface
of the slider facing the disk is also flat. As a result, it is
possible to suppress vertical displacement of the disk, i.e.,
fluttering of the disk, which is caused by fluctuation of pressure
around the disk, thus stably and easily carrying out a focus
control and tracking, for example.
[0245] Thus, the disk can be stably rotated even when the focusing
means or the optical pickup with the focusing means is moved,
thereby providing a recording and reproducing device which can
record and reproduce information stably and desirably even with a
thin disk. Further, the use of a thin disk means a shorter optical
path in the disk, which makes it possible to provide a large margin
of error for a tilt of the disk. As a result, recording density of
the disk can be increased.
[0246] Further, because the first stabilizing board has an opening
which can pass a laser beam in an optical path of the laser beam,
the material of the first stabilizing board will not be limited,
for example, to transparent materials which can pass the laser
beam, and non-transparent materials can be used as well. That is,
the material of the first stabilizing board can be selected from a
wider range of materials, thus enabling the first stabilizing board
to be made from a material with good workability and good
durability.
[0247] Further, because the first stabilizing board has an opening,
a laser beam can pass through the opening without reflecting at the
surface of the first stabilizing board. As a result, the laser beam
can be used more efficiently. For example, compared with the case
where the first stabilizing board does not have an opening and the
laser beam partially reflects at the surface of the first
stabilizing board, information can be recorded and reproduced at
lower light power, thus reducing power consumed in the recording
and reproducing device.
[0248] It is preferable in the recording and reproducing device
that the opening is in the form of a bowl on the optical path of
the laser beam passing through the first stabilizing board.
[0249] According to this arrangement, the area of the opening
facing the disk can be decreased without blocking the laser beam
travelling through the first stabilizing board. This suppresses air
turbulence which may be caused at the opening when the disk is
rotated, thereby suppressing disturbance of air pressure between
the disk and the first stabilizing board. As a result, it is
possible to suppress fluttering of the disk and stabilize rotation
of the disk.
[0250] [Fifth Embodiment]
[0251] The following will describe still another embodiment of the
present invention.
[0252] In FIG. 21, an optical disk 101 is provided as a flexible
disk with a magnetic center hub 102, whereby the optical disk 101
is chucked to a spindle 103 by magnetic coupling. The disk 101 is
rotated by driving the spindle 103. An optical pickup 104 has a
transparent stabilizing board 105 which is provided as a rotation
stabilizing board made of glass with flat and smooth surfaces. The
optical pickup 4 is driven in a radial direction of the optical
disk by a motor such as a linear motor.
[0253] The flexible optical disk 101 is contained in an optical
disk cartridge 106 made of polycarbonate, and an inner wall surface
of the optical disk cartridge 106 opposite the transparent
stabilizing board 105 defines a counter stabilizing surface 107
which is provided as a flat and smooth rotation stabilizing
surface.
[0254] The flexible optical disk 101 is rotated (e.g., about 3000
rpm) between the transparent stabilizing board 105 and the counter
stabilizing surface 107 which is defined by the inner wall surface
of the optical disk cartridge 106, so that the air pressure between
the optical disk 101 and the transparent stabilizing board 105 and
the air pressure between the optical disk 101 and the counter
stabilizing surface 107 balance out, thereby realizing stable
rotation with less fluttering. That is, the optical disk 101, being
flexible, stably rotates at a constant distance (e.g., 20 .mu.m)
from the transparent stabilizing board 105 or counter stabilizing
surface 107. Thus, the optical disk 101 fluctuates less in optic
axis directions than conventionally, thereby attaining easy
focusing.
[0255] FIG. 22 shows the optical disk cartridge 106 of FIG. 21 as
viewed from the side of the optical pickup 104.
[0256] The optical disk cartridge 106 has a first opening 108 for
chucking the center hub 102 of the flexible optical disk 101 to the
spindle 103, and a second opening 109 which is used to position the
optical pickup 104 with the transparent stabilizing board 105 in
the vicinity of the optical disk 101. Further, the optical disk
cartridge 106 is provided with a slide shutter 110 which can be
opened or closed to shut out dusts.
[0257] The optical disk cartridge of the present invention is
adapted so that the inner wall surface of the optical disk
cartridge opposite the second opening 109 defines the counter
stabilizing surface 107, and the first opening 108 and the second
opening 109 are provided only on one surface of the optical disk
cartridge. That is, the slide shutter 110 can be provided only on
one surface of the optical disk cartridge 106 to cover the first
opening 108 and the second opening 109, thereby simplifying the
slide shutter 110.
[0258] FIG. 23 schematically shows a cross section of a magnified
portion of the optical pickup 104 of FIG. 21. Here, the optical
disk 101 may be a ROM disk with a series of pits, which are
recessions on a surface of the substrate, or a write once disk
which employs an organic pigment material for its recording medium,
or a rewritable disk which employs a phase-change material for its
recording medium.
[0259] In the case of the write once disk or rewritable disk, the
optical disk 101 is made up of a disk substrate 111 made of
polyethylene terephthalate having guiding grooves thereon, a
recording medium 112 which is provided on the surface of the
guiding grooves, and a protective layer 113 for protecting the
recording medium 112. The flexible optical disk 101 is stably
rotated between the transparent stabilizing board 105 which is
fixed on an optical pickup casing 114 (one of supporting members of
an objective lens (mentioned later)) and a counter stabilizing
surface 115 which is defined by the inner wall surface of the
optical disk cartridge 106 opposite the transparent stabilizing
board 105, so that the air pressure between the optical disk 1 and
the transparent stabilizing board 105 and the air pressure between
the optical disk 101 and the counter stabilizing surface 115
balance out.
[0260] A laser beam 117 from a light emitting element in an light
emitting and detecting optical system 116 is converged through an
objective lens 118 (focusing unit) to fall on the recording medium
112 of the optical disk 101. A state of reflected light from the
recording medium 112 is detected by a photoreceptor element in the
light emitting and detecting optical system 116 so as to record or
reproduce information.
[0261] Here, the objective lens 118 is fixed on a lens holder 119
(one of supporting members) which is fixed on the optical pickup
casing 114 via a biaxial actuator 120 (another supporting member).
The objective lens 118 is driven in this configuration to carry out
focusing and tracking operations with respect to the guiding
grooves of the optical disk 101.
[0262] Note that, focusing and tracking can be realized to
sufficiently record or reproduce a data signal despite the use of
the biaxial actuator 120 which employs the conventional servo
technique, because the flexible optical disk 101 stably rotates
between the transparent stabilizing board 105 and the counter
stabilizing surface 115 with less fluttering.
[0263] FIG. 24 schematically shows a cross section of a magnified
portion of the optical pickup 104 when a dual lens composed of a
lens 121 and a lens 122 is used to increase numerical aperture NA
of the objective lens, as taught by Japanese Unexamined Patent
Publication No. 308059/1998 (Tokukaihei 10-308059) (published date:
Nov. 17, 1998) ("Document 11" hereinafter).
[0264] The dual lens, composed of the lens 121 and the lens 122,
enables numerical aperture NA to be increased. Specifically, the
numerical aperture NA of the dual lens is preferably not less than
0.7, and more preferably from 0.8 to 0.95. Note that, the numerical
aperture can also be increased with the use of a simple lens.
However, the use of the dual lens makes manufacture of the
objective lens easier. The dual lens is preferably used when the
numerical aperture is to be not less than 0.7 as in the present
embodiment.
[0265] In Document 1, to record or reproduce information, as shown
in FIG. 52, an optical pickup 403 including focusing means (complex
objective lens) which is provided opposite a stabilizing board 402
is positioned in the vicinity of a flexible optical disk 401.
[0266] In this case, the surface of the optical pickup 403 facing
the disk 401 makes up the surface with focusing means such as a
lens element. Such a surface has relatively large irregularities,
which causes the pressure between the optical pickup 403 and the
optical disk 401 to fluctuate when the optical pickup 403 is
positioned in the vicinity of the optical disk 401. This pressure
fluctuation causes the optical disk 401 to flutter in the vicinity
of the optical pickup 403, which leads to a failure to maintain
stable focusing operation, and thus a failure to record and
reproduce information desirably.
[0267] However, according to the arrangement of the present
embodiment, the optical disk 1 is rotated stably by balancing the
air pressure between the optical disk 101 and the transparent
stabilizing board 105 with that between the optical disk 101 and
the counter stabilizing surface 115. This makes it possible to
maintain stable focusing operation and to record and reproduce
information desirably.
[0268] The recording medium 112 shown in FIG. 24 may be a write
once optical disk using an organic pigment material, or a
rewritable optical disk using a phase-change material.
Alternatively, a ROM disk having a series of pits on a substrate
surface may be used as well.
[0269] FIG. 25 schematically shows a cross section of a magnified
portion of the arrangement shown in FIG. 23 when the transparent
stabilizing board 105 is fixed on the optical pickup casing 114 via
a board spring 123.
[0270] In the arrangement shown in FIG. 22, the transparent
stabilizing board 105 is fixed directly on the optical pickup
casing 114. This may damage the optical disk 101, for example, by
scratching the surface of the optical disk 101, when the optical
disk 101 collides with the transparent stabilizing board 105 in
response to external oscillation inflicted on the optical disk
cartridge 106 and the optical disk 101.
[0271] On the other hand, in the arrangement shown in FIG. 25, the
transparent stabilizing board 105 is fixed on the optical pickup
casing 114 via the board spring 123. According to this arrangement,
the board spring 123 acts to absorb the oscillation of the optical
disk 101 when the optical disk cartridge 106 and the optical disk
101 oscillate due to external oscillation, thereby preventing
damage to the optical disk 101 which is caused when the optical
disk 101 collides with the transparent stabilizing board 105 due to
external oscillation.
[0272] The foregoing described the case where the board spring 123
was incorporated in the arrangement of FIG. 22. However, the same
effect can be obtained in the arrangement incorporating the dual
lens as shown in FIG. 22, by fixing the transparent stabilizing
board 105 on the optical pickup casing 114 via the board spring
123.
[0273] FIG. 26 schematically shows a cross section of a magnified
portion of the arrangement of FIG. 24, wherein a portion of the
transparent stabilizing board 105 which passes light has a light
passage opening 124.
[0274] In the arrangements of FIG. 23 through FIG. 25, the laser
beam 117 is required to pass through the transparent stabilizing
board 105, which restricts the material of the transparent
stabilizing board 105 to optically uniform materials, such as
transparent quartz or glass. Another problem is the reflection of
light at the both surfaces of the transparent stabilizing board,
which lowers the efficiency of using the laser beam 117.
[0275] On the other hand, as shown in FIG. 26, the light passage
opening 124 of the transparent stabilizing board 105 enables the
transparent stabilizing board 105 to be made of a non-transparent
material, thus offering a wide selection of materials. For example,
the transparent stabilizing board 105 may be made of an inexpensive
material such as non-transparent reinforced plastic. Further, since
the transparent stabilizing board 105 has no surface at which the
laser beam 117 reflects, the laser beam 117 can be used more
efficiently.
[0276] FIG. 27 shows an arrangement for further stabilizing
rotation of the flexible optical disk 101, wherein the surface of
the optical disk cartridge 106 defining the counter stabilizing
surface 107, i.e., the entire inner surface of the optical disk
cartridge 106 opposite the surface having the opening defines a
first entire stabilizing surface 125. By thus placing the flexible
optical disk 101 and the first entire stabilizing surface 125 of
the optical disk cartridge 106 in close proximity, the optical disk
101 can be rotated further stably.
[0277] In the arrangement of FIG. 21, stable rotation of the
optical disk 101 with less fluttering is realized by rotating the
optical disk 101 between the transparent stabilizing board 105 and
the counter stabilizing surface 107, which is defined by the inner
wall surface of the optical disk cartridge 106, so that the air
pressure between the optical disk 101 and the transparent
stabilizing board 105 balances with that between the optical disk
101 and the counter stabilizing surface 107. However, the optical
disk 101 rotating in the cartridge can move slightly in an area
where the optical disk 101 is not sandwiched by the transparent
stabilizing board 105 and the counter stabilizing surface 107.
[0278] Thus, by the influence of external force such as
oscillation, the flexible optical disk 101 may flutter slightly in
the space of the optical disk cartridge 106, which could result in
instable rotation.
[0279] On the other hand, in the arrangement shown in FIG. 27, the
flexible optical disk 101 is rotated by the spindle 103, which
creates a space of reduced pressure between the flexible optical
disk 101 and the first entire stabilizing surface 125. As a result,
the optical disk 101 is drawn to the first entire stabilizing
surface 125 and stably rotates at a constant distance from the
first entire stabilizing surface 125.
[0280] Thus, fluttering of the flexible optical disk 101 can also
be prevented in an area where the flexible optical disk 101 is not
sandwiched by the transparent stabilizing board 105 and the counter
stabilizing surface 107, thereby attaining desirable recording and
reproducing.
[0281] Here, as with the other embodiments of the present
invention, the thickness of the flexible optical disk 101 is
preferably not less than 30 .mu.m and not more than 400 .mu.m. A
thickness of the optical disk 101 less than 30 .mu.m makes it
difficult for the optical disk 101 to maintain a strength to
withstand rotation. On the other hand, a thickness of the optical
disk 101 exceeding 400 .mu.m makes the optical disk 101 less
flexible, which undermines the effect of suppressing fluttering of
the optical disk 101 by the transparent stabilizing board 105, the
counter stabilizing surface 107, and the first entire stabilizing
surface 125.
[0282] Further, in order for the inner wall of the optical disk
cartridge 106 to serve as the first entire stabilizing surface 125,
the distance between the optical disk 101 and the first entire
stabilizing surface 125 is preferably not less than 10 .mu.m and
not more than 200 .mu.m.
[0283] A distance between the optical disk 101 and the first entire
stabilizing surface 125 less than 10 .mu.m causes the optical disk
101 to collide with the first entire stabilizing surface 125, and
the surface of the optical disk 101 is more likely to be scratched.
On the other hand, a distance between the optical disk 101 and the
first entire stabilizing surface 125 exceeding 200 .mu.m prevents
the first entire stabilizing surface 125 to serve as a stabilizing
board, which may result in instable rotation of the optical disk
101 in the optical disk cartridge 106 due to such factors as
oscillation.
[0284] FIG. 28 shows an arrangement for further stabilizing
rotation of the flexible optical disk 101, wherein the surface of
the optical disk cartridge defining the counter stabilizing surface
107, i.e., the entire inner wall surface of the optical disk
cartridge 106 opposite the surface having an opening defines the
first entire stabilizing surface 125, and the entire inner wall
surface of the optical disk cartridge 106 on the side of the
opening defines a second entire stabilizing surface 126.
[0285] By thus placing the optical disk 101 in the vicinity of the
first entire stabilizing surface 125 and the second entire
stabilizing surface 126 of the optical disk cartridge 106, the
optical disk 101 can be rotated further stably.
[0286] In the arrangement shown in FIG. 27, the flexible optical
disk 101 is placed in the vicinity of the first entire stabilizing
surface 125 to realize stable rotation of the optical disk 101.
However, in an area where the optical disk 101 is not sandwiched
between the transparent stabilizing board 105 and the counter
stabilizing surface 107, the optical disk 101 rotating in the
cartridge can move away from the first entire stabilizing surface
125.
[0287] Thus, by the influence of external force such as
oscillation, the flexible optical disk 101 flutters in the space of
the optical disk cartridge 106, which prevents stable rotation.
[0288] On the other hand, in the arrangement of FIG. 28, stable
rotation of the flexible optical disk 101 with less fluttering is
realized by driving the flexible optical disk 101 to rotate between
the first entire stabilizing surface 125 and the second entire
stabilizing surface 126 by the spindle 103, so that the air
pressure between the optical disk 101 and the first entire
stabilizing surface 125 balances with that between the optical disk
101 and the second entire stabilizing surface 126.
[0289] Thus, fluttering of the flexible optical disk 101 can also
be prevented in an area where the flexible optical disk 101 is not
sandwiched by the transparent stabilizing board 105 and the counter
stabilizing surface 107, thereby attaining desirable recording and
reproducing.
[0290] Here, the thickness of the flexible optical disk 101 is
preferably not less than 30 .mu.m and not more than 400 .mu.m. A
thickness of the optical disk 101 less than 30 .mu.m makes it
difficult for the optical disk 101 to maintain a strength to
withstand rotation. On the other hand, a thickness of the optical
disk 101 exceeding 400 .mu.m makes the optical disk 101 less
flexible, which undermines the effect of suppressing fluttering of
the optical disk 101 by the transparent stabilizing board 105 and
the counter stabilizing surface 107, and by the first entire
stabilizing surface 125 and the second entire stabilizing surface
126.
[0291] Further, in order for the inner wall of the optical disk
cartridge 106 to serve as the first entire stabilizing surface 125
and the second entire stabilizing surface 126, the distance between
the optical disk 101 and the first entire stabilizing surface 125
and the distance between the optical disk 101 and the second entire
stabilizing surface 126 are each preferably not less than 10 .mu.m
and not more than 200 .mu.m.
[0292] A distance between the optical disk 101 and the first entire
stabilizing surface 125 or the second entire stabilizing surface
126 less than 10 .mu.m causes the optical disk 101 to collide with
the first entire stabilizing surface 125 or the second entire
stabilizing surface 126, and the surface of the optical disk 101 is
more likely to be scratched.
[0293] On the other hand, a distance between the optical disk 101
and the first entire stabilizing surface 125 or the second entire
stabilizing surface 126 exceeding 200 .mu.m prevents the first
entire stabilizing surface 125 and the second entire stabilizing
surface 126 to serve as a stabilizing board, which may result in
instable rotation of the optical disk 101 in the optical disk
cartridge 106 due to such factors as oscillation.
[0294] According to the foregoing Fifth Embodiment, an optical disk
device of the present invention, which records and reproduces
information with respect to an optical disk, comprises: rotation
driving means for rotating an optical disk; a focusing unit for
focusing light from a light source on the optical disk; a support
member for supporting the focusing unit; and a rotation stabilizing
board, fixed to the support member so as to be disposed between the
focusing unit with the support member and the optical disk, for
stabilizing rotation of the optical disk.
[0295] That is, in the present invention, the focusing means, i.e.,
the focusing unit and the support member are provided with the
rotation stabilizing board for stabilizing rotation of a flexible
disk, so as to prevent fluttering of the optical disk which may be
caused when the focusing unit and the support member are positioned
in the vicinity of the optical disk, thereby enabling desirable
recording and reproducing.
[0296] Further, in the present invention, by defining the inner
wall of the optical disk cartridge to make up the rotation
stabilizing surface for further stabilizing rotation of the optical
disk, the optical disk can be rotated between the rotation
stabilizing board, which is provided on the support member of the
focusing unit, and the rotation stabilizing surface, which is
defined by the inner wall of the optical disk cartridge, by
balancing the air pressure between the optical disk and the
rotation stabilizing board with that between the optical disk and
the rotation stabilizing surface. This suppresses fluctuation of
pressure which may be generated around the optical pickup, and thus
suppresses fluttering of the flexible optical disk when it is
rotating. As a result, desirable recording and reproducing can be
realized.
[0297] Further, in the optical disk device according to the present
invention, by the provision of the rotation stabilizing board which
is fixed on the support member of the focusing means via a spring,
it is possible to prevent pressure fluctuation which may be caused
around the optical pickup, and to prevent fluttering of the
flexible optical disk when it is rotating. As a result, it is
possible to desirably record and reproduce information and to
completely suppress damage to the optical disk which is caused when
the flexible optical disk collides with the rotation stabilizing
board.
[0298] Further, in the optical disk device according to the present
invention, the focusing unit may be a dual lens composed of two
lenses. This increases numerical aperture NA, thus providing the
optical disk device which is suitable for high-density recording
and reproducing.
[0299] In the present invention, the rotation stabilizing board can
be made of a material, for example, such as transparent quartz and
glass, which can essentially pass light which is focused by the
focusing unit, or made entirely of a material which does not pass
light focused by the focusing unit, so as to instead form a light
passage opening for allowing passage of light. That is, the
rotation stabilizing board can be made of a non-transparent
material, which provides a wider selection of materials and
eliminates from the rotation stabilizing board a reflecting surface
of the laser beam, thereby using the laser beam more
efficiently.
[0300] In the optical disk cartridge which contains a flexible
optical disk in the optical disk device according to the present
invention, one surface of the optical disk cartridge has a first
opening through which the rotation driving means (specifically,
spindle) enters the optical disk cartridge, and a second opening
through which at least the focusing unit enters the optical disk
cartridge. Here, only one surface of the optical disk cartridge has
the first opening and the second opening, and there is no opening
on the other side of the optical disk cartridge. This allows only
one surface of the optical disk cartridge to have a slide shutter
which is used to open and close an opening of the optical disk
cartridge to prevent dusts from entering the optical disk
cartridge. As a result, it is possible to simplify the slide
shutter of the optical disk cartridge.
[0301] Further, in the optical disk cartridge, the inner wall of
the optical disk cartridge opposite the surface with the second
opening may constitute a rotation stabilizing surface. In this
case, the flexible optical disk is placed between the rotation
stabilizing board (transparent stabilizing board) and the inner
wall of the optical disk cartridge. As a result, fluttering of the
flexible optical disk can be suppressed, thus desirably recording
and reproducing information.
[0302] Further, in the optical disk cartridge, the entire surface
of one of inner walls of the optical disk cartridge opposite the
surface with the second opening may constitute a first entire
stabilizing surface with respect to the flexible optical disk. In
this case, the first entire stabilizing surface defining the inner
wall surface of the optical disk cartridge can suppress fluttering
of the flexible optical disk more effectively, thus recording and
reproducing information more stably and more desirably.
[0303] Further, in the optical disk cartridge, the entire surface
of one of inner walls of the optical disk cartridge opposite the
surface with the second opening may constitute a first entire
stabilizing surface with respect to the flexible optical disk, and
the inner wall surface with the second opening may constitute a
second entire stabilizing surface with respect to the flexible
optical disk. In this case, the first entire stabilizing surface
and the second entire stabilizing surface defining the inner wall
surfaces of the optical disk cartridge can suppress fluttering of
the flexible optical disk more effectively, thus recording and
reproducing information more stably and more desirably.
[0304] Here, it is preferable in the optical disk cartridge that
the distance between the flexible optical disk and the first entire
stabilizing surface is not less than 10 .eta.m and not more than
200 .mu.m, the distance between the flexible optical disk and the
second entire stabilizing surface is not less than 10 .mu.m and not
more than 200 .mu.m. In this way, the first and second entire
stabilizing surfaces serve as a stabilizing board of the flexible
optical disk to suppress fluttering of the flexible optical disk
more effectively, thus recording and reproducing information more
stably and more desirably.
[0305] As described, according to the optical disk device of the
present invention, the support member of the focusing unit is
provided with the rotation stabilizing board for stabilizing
rotation of the optical disk, so as to prevent fluttering of the
optical disk which may be caused when the focusing unit and the
support member of the focusing unit are positioned in the vicinity
of the optical disk. As a result, information can be recorded and
reproduced desirably.
[0306] Further, in the present invention, the inner wall of the
optical disk cartridge may define the rotation stabilizing surface
for further stabilizing rotation of the optical disk. In this case,
the flexible optical disk stably rotates between the transparent
stabilizing board and the rotation stabilizing surface which is
defined by the inner wall of the optical disk cartridge on the
opposite side, by balancing the air pressure between the optical
disk and the rotation stabilizing board with the air pressure
between the optical disk and the rotation stabilizing surface. This
makes it possible to suppress pressure fluctuation which occurs
around the optical pickup, and thus fluttering of the flexible
optical disk, thus realizing desirable recording and reproducing of
information.
[0307] Note that, the foregoing embodiments of the present
invention indicated that the first stabilizing board can be
realized with a material other than a transparent material. The
following embodiments will describe the case where a focusing
slider, instead of the transparent stabilizing board 5, is provided
as the first stabilizing board, wherein the focusing slider has the
focusing means (lens, etc.) on the stabilizing board itself and has
the function of the slider.
[0308] [Sixth Embodiment]
[0309] The following will describe yet another embodiment of the
present invention. Note that, the present embodiment describes the
case where the recording and reproducing device is an optical disk
device which records and reproduces information with respect to an
optical disk, not a magneto-optical disk.
[0310] FIG. 29 is a cross sectional view showing relevant part of
an optical disk device according to the present embodiment. As
shown in FIG. 29, the optical disk device of the present embodiment
includes a spindle (rotation driving means) 203, a focusing slider
204, an optical pickup 205, a stabilizing slider 206, and a
suspension 207, so as to record and reproduce information with
respect to a flexible optical disk 201 (simply "optical disk"
hereinafter).
[0311] The optical disk 201 is fixed on the spindle 203 via a
center hub 202 and is rotated by driving the spindle 203. The
focusing slider 204 with focusing means, and the stabilizing slider
206 which is supported by the suspension 207 are disposed with the
optical disk 201 in between.
[0312] The suspension 207 on the opposite end of the stabilizing
slider 206 is fixed to an optical pickup carriage 208. The optical
pickup carriage 208 has the optical pickup 205.
[0313] The focusing slider 204 is fixed on a slider holder 210 via
a first board spring 209. The slider holder 210 is fixed to the
optical pickup carriage 208 via a second board spring 211.
[0314] The focusing slider 204, the optical pickup 205, and the
stabilizing slider 206 are driven by a linear motor or swing arm to
move in a radial direction of the optical disk 201.
[0315] Note that, the focusing slider 204 has the same function as
the transparent stabilizing board 5 used as the first stabilizing
board in the First and Second Embodiments, and has focusing means
for focusing a light beam from the optical pickup 205 on the
optical disk 201. Details of the focusing slider 204 will be
described later.
[0316] As shown in FIG. 30, the optical disk 201 is made up of an
optical disk substrate 212, an optical recording medium 213, and a
protective coat 214. A light beam 215 emitted from the optical
pickup 205 is focused on the optical recording medium 213 by the
focusing means which is fixed on the focusing slider 204, so as to
record, erase, and reproduce information.
[0317] The optical disk substrate 212 is a flexible resin substrate
such as a polyethylene terephthalate (PET) film, and the focal
plane of the optical disk substrate 212 has tracking guiding
grooves, for example, by the 2P method.
[0318] The optical recording medium 213 may be made of a phase
change recording material such as GeSbTe or InAgSbTe, a
magneto-optical recording material such as TbFeCo, a
super-resolution magneto-optical recording material such as TbFeCo
and GdFeCo stacked together in multiple layers, and a write once
recording medium incorporating a pigment-containing organic
material. Further, the optical recording medium 213 may be a read
only optical disk which is prepared by forming pits on the optical
disk substrate 212 together with a reflecting film which is
provided instead of the optical recording medium 213.
[0319] The protective coat 214 is provided to prevent damage to the
optical recording medium 213, which may be caused when the optical
disk 201 collides with the stabilizing slider 206. The protective
coat 214 may be a resin layer, for example, such as a UV curable
resin layer or a resin sheet adhesive layer. Further, a thin film
of SiN, AlN, or SiC may be used as well. Further, a lubricating
coat layer may be additionally provided on the protective coat
214.
[0320] As shown in FIG. 31, the optical pickup 205 has optical
elements including a light emitting element 216, a focusing
tracking light receiving element 217, and a reproduced signal
detecting light receiving element 218. The optical pickup 205 is
fixed on the optical pickup carriage 208, and the light beam 215
from the optical pickup 205 is deflected toward the optical disk
201 by a stand mirror 219 which is disposed and fixed on the slider
holder 210, and the light beam 215 is focused on the optical
recording medium 213 through a first lens 221 and a second lens 222
which are fixed on the focusing slider 204 having a piezoelectric
element 220.
[0321] The focusing slider 204 is fixed on the slider holder 210
via the first board spring 209 which pushes the focusing slider 204
toward the optical disk 201. The stabilizing slider 206 is fixed on
the optical pickup carriage 208 via the suspension 207, and the
stabilizing slider 206 is also pushed toward the optical disk 201.
That is, the focusing slider 204 and the stabilizing slider 206 are
disposed on the both sides of the optical disk 201.
[0322] Thus, an air flow which is generated by rotation of the
optical disk 201 creates an air bearing between the optical disk
201 and the focusing slider 204, and between the optical disk 201
and the stabilizing slider 206. Therefore, access is made in the
radial direction while the optical disk 201 is driven to stably
rotate between the focusing slider 204 and the stabilizing slider
206 at a constant distance from these sliders, by balancing air
pressure between the optical disk 201 and the focusing slider 204
with that between the optical disk 201 and the stabilizing slider
206.
[0323] The slider holder 210 is fixed on the optical pickup
carriage 208 via the second board spring 211 so that the slider
holder 210 can be driven in track direction 223 (radial direction
of the disk).
[0324] To the optical pickup carriage 208 is fixed a pair of
permanent magnets 224, which, with a coil 225 fixed on the slider
holder 210, make up a magnetic circuit. The magnetic circuit serves
as a tracking actuator which enables the slider holder 210 to be
driven in the track direction 223, so as to drive the focusing
slider 204 in track direction 223 with the slider holder 210.
[0325] In the tracking actuator, as shown in FIG. 30 and FIG. 31, a
tracking error signal 226 outputted from the focusing tracking
light receiving element 217 in the optical pickup 205 is inputted
to the control circuit 227, so as to drive the coil 225 according
to the control signal from the control circuit 227, thus driving
(tracking) the slide holder 210 in track direction 223.
[0326] The following describes the focusing slider 204.
[0327] As shown in FIG. 32, the focusing slider 204 is made up of a
slider member 228 and the piezoelectric element 220, wherein the
piezoelectric element 220 is placed between the slider member
228.
[0328] The slider member 228 is made of a material, for example,
such as a metal plate, ceramic plate, or plastic plate with a
thickness in a range of 0.2 to 1.5 mm. Further, the piezoelectric
element 220 may be a stacked piezoelectric element with a thickness
of 0.2 mm to 1.0 mm, for example, such as that taught in Japanese
Unexamined Patent Publication No. 121820/1999 (Tokukaihei
11-121820).
[0329] Further, the slider member 228 at its center has a
perforation 229, wherein the first lens 221 and the second lens 222
are disposed in the perforation 229 in this order with respect to
the optical disk 201.
[0330] The first lens 221 and the second lens 222 are provided to
bridge the piezoelectric element 220, and the distance between the
first lens 221 and the second lens 222 is controlled by applying a
voltage to the piezoelectric element 220. This is focusing, in
which the distance between the first lens 221 and the second lens
222 is adjusted to correct focusing errors on the optical recording
medium 213 which are caused by a change in thickness of the optical
disk substrate 212 making up the optical disk 201, or by a change
in distance between the optical disk 201 and the focusing slider
204.
[0331] As shown in FIG. 30 and FIG. 31, a focus error signal 230
outputted from the focus tracking light receiving element 217 is
inputted to the control circuit 227, and the piezoelectric element
220 is driven by a control signal from the control circuit 227.
[0332] In the present embodiment, the perforation 229 of the
focusing slider 204 is created by forming depressions in the form
of a bowl on the surfaces of the focusing slider 204 respectively
facing the optical disk 201 and the slider holder 210, wherein the
depression of one surface is aligned with the depression of the
other surface on a common central line. The slope of these
depressions making up the perforation 229 is used as a reference
plane to fix the first lens 221 and the second lens 222 on the
focusing slider 204 using an adhesive agent.
[0333] Fixing the first lens 221 and the second lens 222 on the
focusing slider 204 using an adhesive agent makes it easier to
position these lenses and prevents misalignment of the lenses in
the horizontal direction. Thus, there will be no misalignment of
optic axes of the first lens 221 and the second lens 222 in
tracking operations when the first lens 221 and the second lens 222
are driven in the horizontal direction, thus realizing a stable and
desirable focused state.
EXAMPLE 1
[0334] The following describe Examples of the optical disk device
according to the present embodiment. Example 1 describes the case
of the optical disk device of FIG. 16.
[0335] The optical disk 201 was prepared as follows. On optical
disk substrate 212 made of polyethylene terephthalate having a
thickness of 50 .mu.m was formed a 5 .mu.m thick 2P resin layer.
The 2P resin layer had guiding tracks, 20 nm deep, which are spiral
lands and grooves each with a width of 0.23 .mu.m. On the guiding
tracks were formed optical recording medium 213 composed of a 40 nm
thick ZnS--SiO.sub.2 interference film, a 15 nm thick AgInSbTe
phase change recording film, a 20 nm thick ZnS--SiO.sub.2
interference film, and a 120 nm thick Ag reflecting film, which
were stacked in this order. Finally, protective coat 214 made of
SiC was formed in a thickness of 50 nm on the optical recording
medium 213.
[0336] The optical disk 201 so prepared was attached to the spindle
203, as shown in FIG. 1 of the First Embodiment, to drive the
optical disk 201 at 3000 rpm. In order to realize stable rotation,
a stabilizing board (not shown) was provided over the area other
than the area where the focusing slider 204 and the stabilizing
slider 206 were provided.
[0337] Then, the focusing slider 204 and the stabilizing slider 206
were positioned in the vicinity of the optical disk 201 SO as to
create an air bearing by the rotation of the optical disk 201
between the optical disk 201 and the focusing slider 204 and
between the optical disk 201 and the stabilizing slider 206. The
optical disk 201 was rotated so as to balance the air pressure
between the optical disk 201 and the focusing slider 204 with that
between the optical disk 201 and the stabilizing slider 204, so
that a constant distance could be maintained between the optical
disk 201 and the focusing slider 204 and between the optical disk
201 and the stabilizing slider 206. Here, the distance between the
optical disk 201 and the focusing slider 204 and between the
optical disk 201 and the stabilizing slider 206 was about 10 .mu.m
each.
[0338] In this Example, a semiconductor laser with a wavelength of
405 nm was used as the light emitting element in the optical pickup
205, and the first lens 221 and the second lens 222 were designed
to have effective numerical aperture of 0.9. With this arrangement,
the spot size of the light beam on the optical recording medium 213
under optimum condition was 350 nm.
[0339] Here, light was continuously emitted from the semiconductor
laser used as the light emitting element 216 so that the light
which travelled through the first lens 221 struck on the optical
recording medium 213 at 0.5 mW. The light reflected at the optical
disk 201 was used to obtain the tracking error signal 226, which
was obtained from the focusing tracking light receiving element 217
in the optical pickup 205, and the tracking error signal 226 was
inputted to the control circuit 227 with the focus error signal
230. The control circuit 227 carried out the focusing control and
the tracking control in response to these input signals, whereby
the former was effected by feeding electricity to the piezoelectric
element 220 via a pair of focusing control wires 231 and the latter
was effected by feeding electricity to the coil 225 making up the
tracking actuator via a pair of tracking control wires 232.
[0340] According to this method, while focusing and tracking were
carried out, the light emitting element 216 was effected to emit
light in pulses with the peak power of the emitted light pulse
through the first lens 221 at 5 mW, so as to form a series of
recording marks with a diameter of 0.18 .mu.m and a pitch of 0.36
.mu.m on the AgInSbTe phase change recording film of the optical
recording medium 213. After forming the recording marks, the light
emitting element 216 was effected to continuously emit light so
that the power of the light through the first lens 221 was 0.5 mW.
A change in quantity of the reflected light from the optical disk
201 was detected by the reproduced signal detecting light receiving
element 218 (FIG. 15) so as to reproduce information. A reproduced
signal from the reproduced signal detecting light receiving element
218 was evaluated using a spectrum analyzer. The result was a
carrier-to-noise ratio (CNR) of 43 dB, which confirmed that the
optical disk device of the present Example could produce a
reproduced signal which enables the optical disk device to be used
as the recording and reproducing device.
EXAMPLE 2
[0341] In the arrangement of Example 1, as shown in FIG. 32,
information was recorded and reproduced by the
recording/reproducing light which was incident from the side of the
optical disk substrate 212 having flexibility, so as to form a
light beam spot with a diameter of 350 nm on the optical recording
medium 213. This caused aberration due to a change in thickness of
the optical disk substrate 212. Thus, in order to realize stable
focusing, the effective numerical aperture of the dual focusing
lens was set to 0.9.
[0342] In Example 2, as shown in FIG. 33, the recording/reproducing
light was incident from the side of the optical recording medium
213. This prevents the focusing optical system (first lens 221,
second lens 222) from being influenced by a change in thickness of
the optical disk substrate 212, and thus enables the effective
numerical aperture of the dual focusing lens to be increased above
0.9 and the diameter of the light beam spot to be reduced.
[0343] The optical disk 201 in Example 2 was prepared as follows.
On optical disk substrate 212 made of polyethylene terephthalate
having a thickness of 50 .mu.m was formed a 5 .mu.m thick 2P resin
layer. The 2P resin layer had guiding tracks, 15 nm deep, which are
spiral lands and grooves each with a width of 0.20 .mu.m. On the
guiding tracks were formed optical recording medium 213 composed of
a 120 nm thick Ag reflecting film, a 20 nm thick ZnS--SiO.sub.2
interference film, a 15 nm thick AgInSbTe phase change recording
film, and a 40 nm thick ZnS--SiO.sub.2 interference film, which
were stacked in this order. Finally, protective coat 214 made of
SiC was formed with a thickness of 3 nm on the optical recording
medium 213. The protective coat 214, being extremely thin, did not
show a change in thickness which causes aberration.
[0344] As in FIG. 29, the optical disk 201 so prepared was attached
to the spindle 203 to drive the optical disk 201 at 3000 rpm, so as
to maintain a constant distance between the optical disk 201 and
the focusing slider 204 and between the optical disk 201 and the
stabilizing slider 206. The distance between the optical disk 201
and the focusing slider 204 and between the optical disk 201 and
the stabilizing slider 206 was adjusted to 2 .mu.m by adjusting the
pressure exerted by the suspension 207 and the first board spring
209.
[0345] In Example 2, a semiconductor laser with a wavelength of 405
nm was used as the light emitting element 216 in the optical pickup
205, and the first lens 221 and the second lens 222 were designed
to have effective numerical aperture of 1.0. With this arrangement,
the spot size of the light beam on the optical recording medium 213
under optimum condition was 320 nm.
[0346] Here, light was continuously emitted from the semiconductor
laser used as the light emitting element 216 so that the light
which travelled through the first lens 221 struck on the optical
recording medium 213 at 0.4 mW. The light reflected at the optical
disk 201 was used to obtain the tracking error signal 226 and the
focus error signal 230, which was obtained from the focusing
tracking light receiving element 217 in the optical pickup 217, and
the tracking error signal 226 and the focus error signal 230 were
inputted to the control circuit 227. The control circuit 227
carried out the focusing control and the tracking control in
response to these input signals, whereby the former was effected by
feeding electricity to the piezoelectric element 220 via a pair of
focusing control wires 231 and the latter was effected by feeding
electricity to the coils 225 making up the tracking actuator via a
pair of tracking control wires 232.
[0347] According to this method, while focusing and tracking were
carried out, the light emitting element 216 was effected to emit
light in pulses with the peak power of the emitted light pulse
through the first lens 221 at 5 mW, so as to form a series of
recording marks with a diameter of 0.16 .mu.m and a pitch of 0.32
.mu.m on the AgInSbTe phase change recording film of the optical
recording medium 213.
[0348] After forming the recording marks, the light emitting
element 216 was effected to continuously emit light so that the
power of the light through the first lens 221 was 0.4 mW. A change
in quantity of the reflected light from the optical disk 201 was
detected by the reproduced signal detecting light receiving element
218 so as to reproduce information. A reproduced signal from the
reproduced signal detecting light receiving element 218 was
evaluated using a spectrum analyzer. The result was a
carrier-to-noise ratio (CNR) of 45 dB, which confirmed that the
optical disk device of the present Example could produce a
reproduced signal which enables the optical disk device to be used
as the recording and reproducing device. In addition, it was found
in this Example that a higher CNR than that of Example 1 could be
obtained with smaller recording marks than Example 1.
[0349] In the Third Embodiment, the focusing control of the
focusing means (first lens 221, second lens 222) of the focusing
slider 204 is carried out by driving the piezoelectric element 220
which is provided for the focusing slider 204. However, not limited
to this, for example, as shown in FIG. 34 and FIG. 35, the focusing
control may be carried out by a magnetic circuit made up of a
permanent magnet 250 and an air-core coil 251 which are
respectively provided on the opposing surfaces of the focusing
slider 204 and the slider holder 210.
[0350] In FIG. 34, the magnetic circuit for focusing control is
provided by providing the permanent magnet 250 on the side of the
focusing slider 204 and the air-core coil 251 on the side of the
slider holder 210. In FIG. 35, the magnetic circuit for focusing
control is provided by providing the permanent magnet 250 on the
side of the slider holder 210 and the air-core coil 251 on the side
of the focusing slider 204.
[0351] In either case, a control signal is supplied to the air-core
coil 251 to move the focusing slider 204 toward the optical disk
201 by the magnetic effect imparted between the air-core coil 251
and the permanent magnet 250, so as to control the pressure exerted
by the focusing slider 204 on the optical disk 201 and to control
the distance between the focusing slider 204 and the optical disk
201, i.e., focusing control is carried out.
[0352] In this case, as described above, the focusing slider 204 is
moved toward the optical disk 201 by the magnetic circuit which is
made up of the permanent magnet 250 and the air-core coil 251.
Thus, it is not required to provide the first board spring 209
between the slider holder 210 and the focusing slider 204 to press
the focusing slider 204 toward the optical disk 201, as described
in FIG. 29 and elsewhere.
[0353] [Seventh Embodiment]
[0354] The following will describe still another embodiment of the
present invention. Note that, constituting elements having the same
functions as those described in the Sixth Embodiment are given the
same reference numerals and explanations thereof are omitted
here.
[0355] In an optical disk device according to the present
embodiment, as shown in FIG. 36, in order to further stabilize
rotation of flexible optical disk 201, a first inner wall surface
234 and a second inner wall surface 235 of an optical disk
cartridge case 233 are used as a stabilizing board. FIG. 37 is a
plan view of the optical disk cartridge case 233 of FIG. 36.
[0356] The optical disk cartridge case 233 has a first opening 236
for chucking a center hub 202 of the optical disk 201 to a spindle
203, and a second opening 237 which is used to position a focusing
slider 204 and a stabilizing slider 206 in the vicinity of the
optical disk 201. The optical disk cartridge 233 further includes a
slide shutter 238 which can be opened or closed to shield
dusts.
[0357] The foregoing Sixth Embodiment used the stabilizing board
(not shown) to stabilize rotation of the optical disk 201 in an
area other than the area sandwiched between the focusing slider 204
and the stabilizing slider 206. In the present embodiment, on the
other hand, rotation of the optical disk 201 is stabilized by the
first inner wall surface 234 and the second inner wall surface 235
of the optical disk cartridge case 233 which serve as the
stabilizing board of the optical disk 201.
[0358] With the use of the optical disk cartridge case 233, the
optical disk 201 is rotated in such a manner that the air pressure
between the first inner wall surface 234 and the optical disk 201
is balanced with that between the second inner wall surface 235 and
the optical disk 201 in the optical disk cartridge case 233.
[0359] Here, the distance between the first inner wall surface 234
and the optical disk 201 and between the second inner wall surface
235 and the optical disk 201 is set within a range of not less than
10 .mu.m and not more than 200 .mu.m. This enables the optical disk
201 to stably rotate at a midway position between the first inner
wall surface 234 and the second inner wall surface 235 with the
balanced air pressure.
[0360] Note that, the distance between the optical disk 201 and the
first inner wall surface 234 or between the optical disk 201 and
the second inner wall surface 235 less than 10 .mu.m causes a
collision between the optical disk 201 and the first inner wall
surface 234 or second inner wall surface 235 to scratch a surface
of the optical disk 201.
[0361] Further, the distance between the optical disk 201 and the
first inner wall surface 234 or between the optical disk 201 and
the second inner wall surface 235 more than 200 .mu.m results in
more free movement of the optical disk in the optical disk
cartridge case 233. This prevents the first inner wall surface 234
and the second inner wall surface 235 to function as the
stabilizing board, which may result in instable rotation of the
optical disk 201 in the optical disk cartridge case 233 in response
to external disturbance such as oscillation.
[0362] As described, in the present embodiment, rotation of the
optical disk 201 is stabilized by the first inner wall surface 234
and the second inner wall surface 235 of the optical disk cartridge
case 233, so as to suppress shuddering of the optical disk 201 in
the optical disk cartridge case 233 and to realize stable rotation
even in an event of external disturbance such as oscillation.
[0363] In the present embodiment, the optical disk 201 of the Fifth
Embodiment was used to record and reproduce information in the
manner explained in the Sixth Embodiment. The result was the
carrier-to-noise ratio (CNR) of 44.5 dB, thus confirming that the
optical disk device of the present embodiment employing the optical
disk cartridge case 233 is capable of producing a reproduced signal
which enables the optical disk device to be used as the recording
and reproducing device.
[0364] Further, it is evident that the optical disk cartridge case
233 of the present embodiment can be used in the optical disk
device in Example 2 of the Sixth Embodiment.
[0365] Further, the foregoing Sixth and Seventh Embodiments
described the case where the recording and reproducing device was
the optical disk device which records and reproduces information
with respect to a recording disk (optical disk) which does not
employ magnetism. However, the present invention is not just
limited to this arrangement and is also applicable to a
magneto-optical disk device which records and reproduces
information with respect to a recording disk (magneto-optical disk)
which employs magnetism. The following Eighth Embodiment describes
such a magnet-optical disk device.
[0366] [Eighth Embodiment]
[0367] The following will describe yet another embodiment of the
present invention. Note that, in the present embodiment,
constituting elements having the same reference numerals as those
described in the foregoing Sixth and Seventh embodiments are given
the same reference numerals and explanations thereof are omitted
here. Also, the optical disk device described in this embodiment
records and reproduces information with respect to an optical disk
which employs magnetism, i.e., a magneto-optical disk.
[0368] As shown in FIG. 38, the magneto-optical disk device
according to the present embodiment includes a magnetic head 241
composed of a magnetic core 239 and a magnetic coil 240, implanted
in the stabilizing slider 206 of the optical disk device of FIG.
32. The other structure is the same as that shown in FIG. 32.
[0369] In the present embodiment, the magnetic head 241 is arranged
such that the magnetic coil 240, which is a lead wire with a
diameter of 40 .mu.m, is wound around the magnetic core 239, which
is a circular pillar with a diameter of 0.2 mm.
[0370] The magnetic coil 240 of the magnetic head 241 has a pair of
lead wires 242 which are drawn from the side of a suspension 207 of
the stabilizing slider 206, so that the surface of the stabilizing
slider 206 can be made flat. The lead wires 242 are used to apply a
voltage and thus a current through the magnetic coil 240 so as to
generate a recording magnetic field.
[0371] A magneto-optical disk ("optical disk" hereinafter) 201 has
the following construction. On an optical disk substrate 212 made
of polyethylene terephthalate having a thickness of 50 .mu.m, there
is provided a 2P resin layer with a thickness of 5 .mu.m. The 2P
resin layer has guiding tracks, 20 nm deep, which are spiral lands
and grooves each with a width of 0.23 .mu.m. On the guiding tracks
are stacked, in this order, an AlN interference film with a
thickness of 40 nm, a GdFeCo read-out layer with a thickness of 30
nm, an AlN intermediate layer with a thickness of 5 nm, a TbFeCo
recording film with a thickness of 30 nm, an SiN interference film
with a thickness of 20 nm, and a super resolution magneto-optical
recording medium 213 which is made from an Ag reflecting film with
a thickness of 120 nm. Finally, a protective coat 214 made of UV
curable resin is formed in a thickness of 5 .mu.m.
[0372] Thus, the optical disk 201 is a super resolution
magneto-optical disk in which the magnetized information of only a
temperature-increased portion of the recording layer is transferred
to the read-out layer by magneto-static coupling.
[0373] Further, the optical disk 201 may be inserted in the optical
disk cartridge 233 of the Seventh Embodiment to stabilize rotation.
The optical disk 201 inserted in the optical disk cartridge 233 in
this way was used to record and reproduce information, with the
focusing slider 204 having the first lens 221 and the second lens
222 as described in the Seventh Embodiment, and the stabilizing
slider 206 implanted with the magnetic head 241.
[0374] Here, focusing and tracking were carried out with the power
of emitted light through the first lens 221 at 0.5 mW. Information
was recorded by light pulse magnetic modulation, whereby the light
emitting element 216 was caused to emit light in pulses with the
peak power of emitted light through the first lens 221 at 6 mW, and
the magnetic head 241 was caused to generate a recording magnetic
field of about 20 kA/m by applying an AC voltage to the lead wires
242. As a result, a series of record marks with a length of 0.1
.mu.m were formed on the TbFeCo recording film at the pitch of 0.2
.mu.m.
[0375] After forming the record marks, the light emitting element
216 was caused to continuously emit light with the power of emitted
light through the first lens 221 at 0.5 mW. Information was
reproduced by detecting a biased state of reflected light from the
optical disk 201 using a reproduced signal detecting photoreceptor
element 218. The reproduced signal from the reproduced signal
detecting photoreceptor element 218 was analyzed using a spectrum
analyzer. The result was a carrier-to-noise ratio (CNR) of 44.5 dB,
thereby confirming that the reproduced signal enables the
magneto-optical disk of the present embodiment to be used as a
recording and reproducing device.
[0376] Note that, the foregoing described the case where recording
and reproducing are carried out with the light beam 215 which is
incident on the side of the optical disk substrate 212, as shown in
FIG. 32 of the Sixth Embodiment. However, not just limited to this,
as shown in FIG. 33 of the Sixth Embodiment, the light may be
incident from the side of the optical recording medium 213 to
record and reproduce information. In this case, recording density
can be increased with the use of a dual lens having larger
numerical aperture.
[0377] Further, referring to magneto-optical disk devices as shown
in FIG. 39 and FIG. 40, the following will describe the case where
the magnetic field generating element is provided on the side of
the focusing slider 204, as opposed to the stabilizing slider
206.
[0378] In the magneto-optical disk device shown in FIG. 39, an
air-core coil 243 for inducing a recording magnetic field on the
optical recording medium 213 is provided so as to surround the
first lens 221 which is fixed on the focusing slider 204. In the
present embodiment, the air-core coil 243 is a lead wire with a
diameter of 40 .mu.m which is coiled in a depression in the form of
a donut with the inner diameter .phi.=0.15 mm, outer diameter
.phi.=1.5 mm, and depth=0.5 mm in the focusing slider 204.
[0379] In order to improve flatness of the slider, lead wires 244
of the air-core coil 243 are extended through lead wire passage 245
which is formed with a diameter of 0.2 mm at the depression of the
focusing slider 204, and are continuously extended to the surface
of the focusing slider 204 opposite the slider holder 210. The lead
wires 244 are used to apply a voltage and thus a current through
the air-core coil 243 to generate a recording magnetic field.
[0380] As with the Sixth Embodiment, the optical disk 201 was
inserted in the optical disk cartridge 233 to evaluate recording
and reproducing ability. As the focusing means, the first lens 211
and the second lens 222 were used as in the Sixth Embodiment.
[0381] Here, focusing and tracking were carried out with the power
of emitted light through the first lens 221 at 0.5 mW. Information
was recorded by light pulse magnetic modulation, whereby the light
emitting element 216 was caused to emit light in pulses with the
peak power of emitted light through the first lens 221 at 6 mW, and
the air-core coil 243 was caused to generate a recording magnetic
field of about 10 kA/m by applying an AC voltage to the lead wires
244. As a result, a series of record marks with a length of 0.1
.mu.m were formed on the TbFeCo recording film at the pitch of 0.2
After forming the record marks, the light emitting element 216 was
caused to continuously emit light with the power of emitted light
through the first lens 221 at 0.5 mW. Information was reproduced by
detecting a biased state of reflected light from the optical disk
201 using a reproduced signal detecting photoreceptor element 218.
The reproduced signal from the reproduced signal detecting
photoreceptor element 218 was analyzed using a spectrum analyzer.
The result was a carrier-to-noise ratio (CNR) of 41 dB, thereby
confirming that the reproduced signal enables the magneto-optical
disk of the present embodiment to be used as a recording and
reproducing device.
[0382] Note that, the foregoing described the case where the
magneto-optical disk device of FIG. 39 carries out recording and
reproducing with the light beam 215 which is incident on the side
of the optical disk substrate 212. However, not just limited to
this, as shown in FIG. 33 of the Sixth Embodiment, the light may be
incident from the side of the optical recording medium 213 to
record and reproduce information. In this case, recording density
can be increased with the use of a dual lens having larger
numerical aperture.
[0383] Further, the foregoing described the case where the focusing
slider 204 of the magneto-optical disk device of FIG. 39 is
provided with the air-core coil 243 as the magnetic field
generating element. The following describes a way to improve the
intensity of a magnetic field (recording magnetic field intensity)
with reference to FIG. 40.
[0384] In the magneto-optical disk device of FIG. 40, in order to
improve intensity of the magnetic field, a soft magnetic material
246 is implanted in the stabilizing slider 206 in the arrangement
of the magneto-optical disk device shown in FIG. 39.
[0385] In the present embodiment, an MnZn ferrite was used as the
soft magnetic material 246 to record and reproduce information. By
thus implanting the soft magnetic material 246 in the stabilizing
slider 206, the soft magnetic material 246 is magnetized by the
magnetic field generated by the air-core coil 243, thus applying a
larger magnetic field to the optical recording medium 213 which is
to record information. Application of a voltage to the air-core
coil 243 under the same condition as that in the magneto-optical
disk device shown in FIG. 39 generated the recording magnetic field
of 20 kA/m.
[0386] As with the magneto-optical disk device of FIG. 39, the
magneto-optical disk device of FIG. 40 was used to form a series of
record marks with a length of 0.1 .mu.m on the TbFeCo recording
film at the pitch of 0.2 .mu.m of the optical recording medium 213
by magnetic filed modulation recording, and a reproduced signal
from the reproduced signal detecting photoreceptor element 218 was
analyzed using a spectrum analyzer. The result was a
carrier-to-noise ratio (CNR) of 44.5 dB. Thus, it was found that
the reproduced signal obtained in the magneto-optical disk device
of FIG. 40 is of a higher quality than that of the magneto-optical
disk device of FIG. 39.
[0387] Note that, the foregoing described the case where the
magneto-optical disk device of FIG. 40 carried out recording and
reproducing with the light beam 215 which is incident on the side
of the optical disk substrate 212. However, not just limited to
this, as shown in FIG. 33 of the Sixth Embodiment, the light may be
incident from the side of the optical recording medium 213 to
record and reproduce information. In this case, recording density
can be increased with the use of a dual lens having larger
numerical aperture.
[0388] According to the foregoing Sixth through Eighth Embodiments,
a recording and reproducing device of the present invention, in a
recording and reproducing device which records and reproduces
information by projecting a laser beam on a disk being rotated,
comprises: a stabilizing slider which is disposed to face the disk
and supported to oscillate, a surface of the stabilizing slider
facing the disk being flat.
[0389] According to this arrangement, rotation of the disk causes
an air flow between the disk and the stabilizing slider, and an air
bearing is created between the stabilizing slider and the disk
because the surface of the stabilizing slider facing the disk is
flat. Further, since the stabilizing slider is supported to
oscillate, the stabilizing slider can be moved to always maintain a
constant distance from the disk when the disk is rotating:
[0390] Thus, the disk rotates in such a way that a constant
distance is maintained between the stabilizing slider and the disk.
This suppresses fluttering of the disk even when the disk is
rotating at high speed, thus stably recording and reproducing
information.
[0391] Further, a stabilizing board may be provided opposite the
stabilizing slider via the disk.
[0392] In this case, just as the air bearing is created between the
stabilizing slider and the disk, an air bearing is also created
between the stabilizing board and the disk when the disk is
rotating. Here, the pressure between the stabilizing slider and the
disk and the pressure between the stabilizing board and the disk
balance out, so that the disk rotates at a constant distance from
the stabilizing slider and the stabilizing board. As a result,
fluttering of the disk can be prevented when the disk is rotating,
thus further stabilizing rotation of the disk.
[0393] The stabilizing board may be adapted so that it makes up a
slider which is supported to oscillate and has a surface facing the
stabilizing slider.
[0394] In this case, as with the stabilizing slider, the
stabilizing board is a slider which is supported to oscillate, and
therefore the stabilizing board can move to always maintain a
constant distance from the disk. Thus, the disk rotates at a
constant distance from the stabilizing board and the disk. As a
result, fluttering of the disk can be suppressed even when the disk
is rotating at high speed, thus stably recording and reproducing
information.
[0395] Thus, by providing the stabilizing board as a slider, in
addition to the stabilizing slider, the distance between the disk
and the stabilizing slider and the distance between the disk and
the stabilizing board can easily be maintained constant when the
disk is rotating. That is, it is possible to easily provide a
recording and reproducing device which can stably record and
reproduce information by suppressing fluttering of the disk during
rotation of the disk.
[0396] The slider may be a focusing slider which is provided with
focusing means for focusing a laser beam on the disk.
[0397] In this case, because the focusing means has the slider,
fluttering of the disk due to pressure fluctuation which is caused
by the movement of the focusing means can be suppressed by the
slider. That is, because the movement of the focusing means is
accompanied by the movement of the slider, the pressure fluctuation
caused by the focusing means can be absorbed by the slider, thus
suppressing fluttering of the disk when the disk is rotating.
[0398] As a result, information can be stably recorded and
reproduced with respect to the rotating disk.
[0399] The focusing slider may include a first lens and a second
lens which are provided as the focusing means, the first lens and
the second lens being separated from each other by a predetermined
distance, and a piezoelectric element layer for controlling the
first lens and the second lens.
[0400] In this case, by focusing and projecting light using the
dual lens composed of the first lens and the second lens to record
or reproduce information, it is possible to increase numerical
aperture, reduce spot size of a light beam, and increase recording
density. Further, by controlling the distance between the first
lens and the second lens using the piezoelectric element layer, it
becomes possible to correct out-of-focus due to uneven thickness of
the substrate or coat layer.
[0401] The stabilizing slider may be provided with a magnetic field
generating element for generating a magnetic field.
[0402] This enables the present invention to be applicable to a
magneto-optical disk incorporating a recording medium which
requires a magnetic field for recording.
[0403] Further, the stabilizing board may be provided with an
air-core coil as a magnetic field generating element for generating
a magnetic field.
[0404] Further, in addition to the stabilizing board provided with
the air-core coil for generating a magnetic field, the stabilizing
slider may be provided with a soft magnetic material.
[0405] In this case, by the magnetic fields respectively generated
from the air-core coil of the stabilizing board and by the soft
magnetic material of the stabilizing slider, the intensity of the
recording magnetic field applied to the magneto-optical disk can be
increased, thereby improving quality of the reproduced signal.
[0406] Further, in the disk cartridge of the present invention
which contains a disk in a cartridge, the disk is exposed from the
disk cartridge when recording or reproducing information, the
cartridge has inner wall surfaces which define a stabilizing board
for creating a space of reduced pressure between the disk and the
inner wall surfaces.
[0407] According to this arrangement, the stabilizing board which
is defined by the inner wall surfaces of the cartridge suppresses
fluttering of the disk more effectively when the disk is rotating,
thus recording and reproducing information more stably and more
desirably.
[0408] Here, rotation of the disk can be further stabilized when
the distance between the disk and each inner wall surface of the
disk cartridge is not less than 10 .mu.m and not more than 200
.mu.m.
[0409] [Ninth Embodiment]
[0410] The following will describe yet another embodiment of the
present invention.
[0411] As shown in FIG. 41, a recording and reproducing device of
the present embodiment includes a flexible optical disk 301 with a
magnetic center hub 302. The flexible optical disk 301 is chucked
to a spindle 303 by magnetic coupling, and is rotated by driving
the spindle 303. An optical pickup 304 with a transparent
stabilizing board 305 made of glass or quartz is fixed on a support
section 306. A slider 307 which is provided as another rotating
stabilizing board is disposed opposite the transparent stabilizing
board 305, and is fixed on the support section 306 via a suspension
308.
[0412] The suspension 308 is provided to press the slider 307 with
such a force that the slider 307 moves toward the transparent
stabilizing board 305. This enables the optical disk 301 to be
stably rotated, by balancing the air pressure between the optical
disk 301 and the transparent stabilizing board 305 with that
between the optical disk 301 and the slider 307.
[0413] That is, the optical disk 301, being flexible, stably
rotates while maintaining an almost constant distance from the
transparent stabilizing board 305. Thus, the optical disk 301
fluctuates less in optic axis directions than conventionally, thus
attaining easier focusing.
[0414] The support section 306 is driven by a driving device (not
shown) to guide the optical pickup 304 and the slider 307 to a
predetermined position of the optical disk 301.
[0415] FIG. 42 schematically shows a cross section of a magnified
portion of the optical pickup 304 and the slider 307 of FIG. 41.
Here, the optical disk 301 may be a ROM disk with a series of pits,
which are recessions on a surface of the substrate, or a write once
disk which employs an organic pigment material for its recording
medium, or a rewritable disk which employs a phase-change material
for its recording medium.
[0416] In the case of the write once disk or rewritable disk, the
optical disk 301 is made up of a disk substrate 309 made of
polyethylene terephthalate having guiding grooves thereon, a
recording medium 310 which is provided on the surface of the
guiding grooves, and a protective layer 311 for protecting the
recording medium 310.
[0417] The flexible optical disk 301 is stably rotated between the
transparent stabilizing board 305 which is fixed on an optical
pickup casing 318 and the slider 307 which is under the pressure of
the suspension 308, so that the air pressure between the optical
disk 301 and the transparent stabilizing board 305 and the air
pressure between the optical disk 301 and the slider 307 balance
out.
[0418] A laser beam 313 from a light emitting element in an light
emitting and detecting optical system 312 is converged through a
first objective lens 314 and a second objective lens 315 to fall on
the recording medium 310 of the optical disk 301. A state of
reflected light from the recording medium 310 is detected by a
photoreceptor element in the light emitting and detecting optical
system 312 so as to record or reproduce information.
[0419] The first objective lens 314 is fixed on the transparent
stabilizing board 305 using an adhesive, etc. The second objective
lens 315 is fixed on a lens holder 316. The lens holder 316 fixed
on the optical pickup casing 318 via a biaxial actuator 317 allows
the second objective lens 315 to carry out focusing and tracking
operations with respect to the guiding grooves of the optical disk
301.
[0420] Note that, focusing and tracking can be realized to
sufficiently record or reproduce a data signal despite the use of
the biaxial actuator 317 which employs the conventional servo
technique, because the flexible optical disk 301 stably rotates
between the transparent stabilizing board 305 and the slider 307
with less fluttering.
[0421] In FIG. 42, the first objective lens 314 is fixed at the
depression of the transparent stabilizing board 305. What is
required here is that the light beam 313 is focused on the surface
of the recording medium 310 by a focusing system composed of the
second objective lens 315, the first objective lens 314, and the
transparent stabilizing board 305.
[0422] FIG. 43 schematically shows a cross section of a magnified
portion of the optical pickup 304 and the slider 307 when the
recording medium of the optical disk 301 is a magneto-optical
recording medium.
[0423] Referring to FIG. 43, recording of information in the
magneto-optical disk requires a recording magnetic field. To this
end, a magnetic head 319 is implanted in the slider 307, so as to
enable a recording magnetic field to be applied on a portion of the
magneto-optical disk where the light beam 313 is focused. The other
structure, except for the magnetic head 319, is the same as that
shown in FIG. 42, whereby the flexible optical disk 301 is stably
rotated between the transparent stabilizing board 305 and the
slider 307 with less fluttering.
[0424] Therefore, focusing and tracking operations are possible
with the use of the biaxial actuator 317 which employs the
conventional servo technique, and the recording magnetic field
which is applied on a focusing position of the light beam by the
magnetic head 319 implanted in the slider 307 enables recording and
reproducing of a data signal with respect to a magneto-optical
recording medium.
[0425] FIG. 44 schematically shows a cross section of a magnified
portion of the arrangement shown in FIG. 43, when the transparent
stabilizing board 305 is fixed on the optical pickup casing 318 via
a board spring 320.
[0426] In the arrangement shown in FIG. 43, the transparent
stabilizing board 305 is fixed directly on the optical pickup
casing 318. This may cause the optical disk 301 to oscillate in
response to oscillation of the slider 307 caused by external force,
and in the worst case, the optical disk 301 may collide with the
transparent stabilizing board 305 to damage the surface of the
optical disk 301, for example, by scratching it.
[0427] On the other hand, in the arrangement shown in FIG. 44, the
transparent stabilizing board 305 is fixed on the optical pickup
casing 318 via the board spring 320. According to this arrangement,
the board spring 320 acts to absorb the oscillation of the optical
disk 301 when the optical disk 301 oscillates in response to
oscillation of the slider 7 caused by external force, thereby
preventing damage to the optical disk 301 which is caused when the
optical disk 301 collides with the transparent stabilizing board
305 due to external oscillation.
[0428] The foregoing described the case where the board spring 320
was incorporated in the arrangement of FIG. 43. However, the same
effect can be obtained in the arrangement shown in FIG. 42, by
fixing the transparent stabilizing board 305 on the optical pickup
casing 318 via the board spring 320.
[0429] FIG. 45 shows an arrangement where a focusing actuator and a
tracking actuator are separately provided to improve focusing of
the light beam 313.
[0430] In the optical disk device of FIG. 42, FIG. 43, or FIG. 44,
driving of the objective lenses for tracking moves only the second
objective lens 315 in a track direction. As a result, the optic
axes of the first and second objective lenses 314 and 315 do not
align, which changes a focusing state of a light beam spot. Thus,
when there is large deviation of guiding tracks in the rotation of
the optical disk 301, it may become impossible to stably record or
reproduce information.
[0431] In light of this drawback, in the optical disk device of
FIG. 45, the transparent stabilizing board 305 is fixed on a
transparent stabilizing board support member (intermediate support
member) 323, and the second objective lens 315, which is fixed on
the lens holder 325, is fixed on the transparent stabilizing board
support member 323 via a focusing actuator 324, and the transparent
stabilizing board support member 323 is fixed to the optical pickup
casing (main support member) 321 via a tracking actuator 322.
[0432] In this case, in focusing, the second objective lens 315 is
moved only in the focusing direction with respect to the first
objective lens 314, and the transparent stabilizing board 305, the
first objective lens 314, and second objective lens 315, which are
fixed on the transparent stabilizing board support member 323, are
integrally moved in a track direction. Therefore, the optic axes of
the first and second objective lenses 314 and 315 align, thus
stably recording and reproducing information even when there is
large deviation in guiding tracks in rotation of the optical disk
301.
[0433] FIG. 45 describes the arrangement where the magnetic head
319 is implanted in the slider 307. However, the same effect can
also be obtained by the arrangement in which the magnetic head 319
is not implanted.
[0434] Further, FIG. 45 describes the case where the transparent
stabilizing board 305 is directly fixed to the transparent
stabilizing board support member 323. However, the transparent
stabilizing board 305 may be fixed to the transparent stabilizing
board support member 323 via the board spring 320 as in the
arrangement of FIG. 44. In this case, the board spring 320 acts to
absorb the oscillation of the optical disk 301, and thus prevents
damage to the optical disk 301, which is caused when the optical
disk 301 collides with the transparent stabilizing board 305 in
response to external oscillation.
[0435] FIG. 46 and FIG. 47 are a cross sectional view and a plan
view, respectively, explaining an arrangement which additionally
includes an entire rotation stabilizing board 326 for the purpose
of further stabilizing rotation of the flexible optical disk 301.
The entire rotation stabilizing board 326 includes a first opening
327 which is used to chuck the center hub 302 of the optical disk
301 to the spindle 303, and a second opening 328 which is used to
position the optical pickup 304 with the transparent stabilizing
board 305 in the vicinity of the optical disk 301. FIG. 46 is a
cross section taken along a center line of the second opening
328.
[0436] By thus providing the entire rotation stabilizing board 326,
rotation of the flexible optical disk 301 fixed to the center hub
302, rotated by the spindle 303, creates a space of reduced
pressure between the flexible optical disk 301 and the entire
rotation stabilizing board 326. Such reduced pressure draws the
optical disk 301 toward the entire rotation stabilizing board 326
to enable the optical disk 301 to stably rotate at a constant
distance from the entire rotation stabilizing board 326, thus
suppressing fluttering of the optical disk 301.
[0437] In this case, as in FIG. 41, the slider 307 is pushed toward
the transparent stabilizing board 305 by the suspension 308 with
such a force that the air pressure between the optical disk 301 and
the transparent stabilizing board 305 and that between the optical
disk 301 and the slider 307 are balanced, thus stably rotating the
optical disk 301. The optical disk 301 is stably rotated in this
manner at a distance from the transparent stabilizing board 305 and
the slider 307, which realizes stable rotation of the optical disk
301 between the transparent stabilizing board 305 and the slider
307, and thus realizes more desirable recording and
reproducing.
[0438] Here, the optical pickup 304 with the transparent
stabilizing board 305 and the slider 307 may be switched in their
positions with respect to the flexible optical disk 301. In this
case, the second opening becomes an opening which is used to
position the slider 307 in the vicinity of the optical disk
301.
[0439] FIG. 48 and FIG. 49 are a cross sectional view and a plan
view, respectively, explaining an arrangement in which the entire
rotation stabilizing board 326 and the optical disk cartridge case
329 are integrally provided in the arrangement of FIG. 46 and FIG.
47 which additionally includes the entire rotation stabilizing
board 326 for the purpose of further stabilizing rotation of the
flexible optical disk 301.
[0440] The optical disk cartridge 329 is made of polycarbonate, and
includes a first opening 327 which is used to chuck the center hub
302 of the optical disk 301 to the spindle 303, a second opening
328 which is used to position the optical pickup 304 with the
transparent stabilizing board 305 in the vicinity of the optical
disk 301, and a third opening 330 which is used to position the
slider 307 in the vicinity of the optical disk 301 at a position
opposite the second opening 328. FIG. 49 is a cross section taken
along a central line of the second opening 328.
[0441] The optical disk cartridge 329 further includes a slide
shutter 331 which can be opened or closed to shut out dusts. In
this case, the entire rotation stabilizing board 326 which is
integrally provided with the optical disk cartridge case 329 acts
in the same way as the entire rotation stabilizing board 326 shown
in FIG. 46 and FIG. 47. As a result, it is possible to more stably
rotate the optical disk 301 (e.g., at about 3000 rpm) between the
transparent stabilizing board 305 and the slider 307 while
maintaining an almost constant distance (e.g., 20 .mu.m) from these
members, thus realizing more desirable recording and
reproducing.
[0442] Further, when the optical disk cartridge case 329 containing
the optical disk 301 is taken out of the recording and reproducing
device, the slide shutter 331 can be closed to protect the optical
disk 301 from dusts more effectively.
[0443] Here, the optical pickup 304 with the transparent
stabilizing board 305 and the slider 307 may be switched in their
positions with respect to the optical disk 301. In this case, the
second opening 328 becomes an opening which is used to position the
slider 307 in the vicinity of the optical disk 301, and the third
opening 330 becomes an opening which is used to position the
optical pickup 304 with the transparent stabilizing board 305 in
the vicinity of the optical disk 301.
[0444] FIG. 50 and FIG. 51 are a cross sectional view and a plan
view, respectively, explaining an arrangement incorporating an
optical disk cartridge case 332 for realizing more stable rotation
of the optical disk 301 and a thinner optical disk cartridge.
[0445] As with FIG. 48 and FIG. 49, the optical disk cartridge 332
includes a first opening 327 which is used to chuck the center hub
302 of the optical disk 301 to the spindle 303, a second opening
328 which is used to position the optical pickup 304 with the
transparent stabilizing board 305 in the vicinity of the optical
disk 301, and a third opening 330 which is used to position the
slider 307 in the vicinity of the optical disk 301 at a position
opposite the second opening 328. FIG. 50 is a cross section taken
along a central line of the second opening 328.
[0446] The optical disk cartridge case 332 further includes a slide
shutter 331 which can be opened or closed to shut out dusts.
[0447] In the arrangement of FIG. 48 and FIG. 49, the flexible
optical disk 301 is drawn to the entire rotation stabilizing board
326 and is rotated at a constant distance from the entire rotation
stabilizing board 326, which suppresses fluttering of the optical
disk 301. However, since the distance between the flexible optical
disk 301 and the inner wall of the optical disk cartridge case 329
on the other side of the entire rotation stabilizing board 326 is
wider, the flexible optical disk 301 flutters in the optical disk
cartridge case 329 by the influence of an external force such as
oscillation. As a result, stable rotation of the optical disk 301
suffers.
[0448] In the arrangement as shown in FIG. 50 and FIG. 51 of the
present embodiment, a space inside the optical disk cartridge case
332 is restricted to suppress fluttering. By this restriction of
the space inside the optical disk cartridge case 332, both the
upper and lower inner walls of the optical disk cartridge case 332
serve as the entire rotation stabilizing board, which suppresses
fluttering of the optical disk 301 and enables the optical disk 301
to be rotated more stably.
[0449] Here, in order for the optical disk 301 to be flexible, the
thickness of the optical disk 301 is preferably not less than 30
.mu.m and not more than 400 .mu.m. A thickness less than 30 .mu.m
makes it difficult to maintain sufficient strength for the optical
disk 301 to withstand rotation. On the other hand, a thickness of
the optical disk 301 exceeding 400 .mu.m makes the optical disk 301
less flexible, which undermines the effect of suppressing
fluttering of the optical disk 301 by the entire rotation
stabilizing board.
[0450] Further, in order for both the upper and lower inner walls
of the optical disk cartridge case 332 to serve as the entire
rotation stabilizing board, it is preferable that the distance
between the optical disk 301 and the upper inner wall of the
optical disk cartridge case 332, and the distance between the
optical disk 301 and the lower inner wall of the optical disk
cartridge case 332 are not less than 10 .mu.m and not more than 200
.mu.m.
[0451] A distance between the optical disk 301 and upper or lower
inner wall of the optical disk cartridge 332 less than 10 .mu.m
causes the optical disk 301 to collide with the upper or lower
inner wall of the optical disk cartridge case 332, and the surface
of the optical disk 301 is more likely to be scratched.
[0452] On the other hand, a distance between the optical disk 301
and the upper or lower inner wall of the optical disk cartridge
case 332 exceeding 200 .mu.m prevents the upper and lower inner
walls of the optical disk cartridge case 332 to serve as a
stabilizing board, which may result in instable rotation of the
optical disk 301 in the optical disk cartridge case 332.
[0453] Here, the optical pickup 304 with the transparent
stabilizing board 305 and the slider 307 may be switched in their
positions with respect to the flexible optical disk 301. In this
case, the second opening 328 becomes an opening which is used to
position the slider 307 in the vicinity of the optical disk 301,
and the third opening 330 becomes an opening which is used to
position the optical pickup 304 with the transparent stabilizing
board 305 in the vicinity of the optical disk 301.
[0454] According to the foregoing Ninth Embodiment, an optical disk
device of the present invention, in an optical disk device which
records and reproduces information with respect to a flexible
optical disk, comprises: rotation driving means for rotating an
optical disk; a focusing unit for focusing light from a light
source on the optical disk; a support member for supporting the
focusing unit; and a transparent rotation stabilizing board, fixed
to the support member so as to be disposed between the focusing
unit with the support member and the optical disk, for stabilizing
rotation of the optical disk, wherein the focusing unit includes a
first objective lens and a second objective lens, the first
objective lens being fixed to the support member via the
transparent rotation stabilizing board, and the second objective
lens being fixed to the support member via an actuator for driving
the lenses.
[0455] That is, in the present invention, a transparent rotation
stabilizing board for stabilizing rotation of the flexible optical
disk is provided on the focusing means, i.e., the focusing unit and
the support member of the focusing unit, so as to prevent
fluttering of the optical disk which may be caused when the
focusing unit and the support member of the focusing unit are
positioned in the vicinity of the optical disk, and thereby enables
desirable recording and reproducing. Further, the focusing unit is
composed of the first objective lens and the second objective lens,
wherein the first objective lens is attached to the support member
via the transparent rotation stabilizing board, and the transparent
rotation stabilizing board is fixed with respect to the optical
disk. This prevents fluttering of the optical disk further
effectively to realize desirable recording and reproducing. The
second objective lens is used to focus light from the light source
on the optical disk by driving actuators of the lens, i.e., a
biaxial driving actuator or focusing and tracking actuators.
Further, in the present invention, another rotation stabilizing
board, e.g., slider, for further stabilizing rotation of the
optical disk is provided on the opposite side of the transparent
rotation stabilizing board via the optical disk. Thus, the flexible
optical disk rotates between the rotation stabilizing board and the
slider to balance the air pressure between the optical disk and the
transparent rotation stabilizing board and that between the optical
disk and the slider. As a result, pressure fluctuation which occurs
around the optical pickup can be suppressed to suppress fluttering
of the flexible optical disk when it is rotating, thus realizing
desirable recording and reproducing. Further, in the present
invention, because the dual lens composed of the first objective
lens and the second objective lens is used for the focusing unit,
numerical aperture can be increased to 0.7 or greater, thereby
realizing a high-density optical disk recording and reproducing
device with a small light beam spot size.
[0456] Further, in the optical disk device according to the present
invention, the transparent rotation stabilizing board is fixed to
the support member of the focusing means via a spring. Thus,
pressure fluctuation which occurs around the optical pickup can be
suppressed to suppress fluttering of the rotating flexible optical
disk. As a result, it is possible to record and reproduce
information desirably and to completely suppress damage to the
optical disk which is caused when the flexible optical disk
collides with the transparent rotation stabilizing board.
[0457] Further, in the optical disk device according to the present
invention, the first objective lens is attached to the transparent
rotation stabilizing board, and the second objective lens is
attached to the support member (intermediate support member) via
the focusing actuator, and the support member is attached to
another support member (main support member) via the tracking
actuator. Thus, the first objective lens is driven only in the
focus direction with respect to the second objective lens, which
prevents misalignment of optic axes when the objective lenses are
moved in the radial direction of the disk in tracking, thus
realizing more stable recording and reproducing.
[0458] In the optical disk device of the present invention, the
transparent rotation stabilizing board is fixed to the support
member of the focusing unit via a spring. This suppresses pressure
fluctuation which occurs around the optical pickup, and thus
suppresses fluttering of the flexible optical disk when it is
rotating. As a result, it is possible to realize desirable
recording and reproducing, and to completely suppress damage to the
optical disk which is caused when the flexible optical disk
collides with the transparent rotation stabilizing board.
[0459] Further, in the optical disk device of the present
invention, a magnetic field generating element is embedded in the
slider. This enables a recording magnetic field to be generated
from the magnetic field generating element when the recording
medium of the optical disk is a magneto-optical recording medium.
This makes the optical disk device of the present invention to be
applicable to an optical disk which employs a magneto-optical
recording medium.
[0460] Further, in the optical disk device of the present
invention, there is provided the entire rotation stabilizing board
on the opposite side of the optical disk. This stabilizes rotation
of the flexible optical disk in an area other than the area
sandwiched between the slider and the transparent rotation
stabilizing board, thus recording and reproducing information more
stably and more desirably.
[0461] Further, in the optical disk device of the present
invention, one of or both inner wall surfaces of the optical disk
cartridge containing the optical disk may define the entire
rotation stabilizing board of the flexible optical disk. This
suppresses fluttering of the optical disk more effectively.
[0462] Further, in the optical disk device of the present
invention, the distance between the optical disk and each inner
wall surface of the optical disk cartridge (casing) is not less
than 10 .mu.m and not more than 200 .mu.m. This enables the entire
rotation stabilizing surface defined by the inner wall surfaces of
the optical disk cartridge to suppress fluttering of the optical
disk more effectively, thus recording and reproducing information
more stably and more desirably.
[0463] As described, in the present invention, the rotation
stabilizing board for stabilizing rotation of the flexible optical
disk is provided on the focusing means, i.e., the focusing unit and
the support member of the focusing unit, wherein the focusing unit
is composed on the first objective lens and the second objective
lens, and the first objective lens is attached to the support
member via the transparent rotation stabilizing board, and the
transparent rotation stabilizing board is fixed with respect to the
optical disk. As a result, fluttering of the optical disk can be
prevented to realize desirable recording and reproducing.
[0464] The second objective lens is used to focus light from the
light source on the optical disk by driving actuators of the lens,
i.e., a biaxial driving actuator or focusing and tracking
actuators.
[0465] Further, another rotation stabilizing board, e.g., slider,
for further stabilizing rotation of the optical disk is provided on
the opposite side of the transparent rotation stabilizing board via
the optical disk. Thus, the flexible optical disk rotates between
the rotation stabilizing board and the slider to balance the air
pressure between the optical disk and the transparent rotation
stabilizing board and that between the optical disk and the slider.
As a result, pressure fluctuation which is generated around the
optical pickup can be suppressed to suppress fluttering of the
flexible optical disk when it is rotating, thus realizing desirable
recording and reproducing. Further, in the present invention,
because the dual lens composed of the first objective lens and the
second objective lens is used for the focusing unit, numerical
aperture can be increased to 0.7 or greater, thereby realizing a
high-density optical disk recording and reproducing device with a
small light beam spot size.
[0466] The invention being thus described, it will be obvious that
the same way may be varied in many ways. Such variations are not to
be regarded as a departure from the spirit and scope of the
invention, and all such modifications as would be obvious to one
skilled in the art are intended to be included within the scope of
the following claims.
* * * * *